Most often, the problems and complications will be connected with:
- the condition and shape in which the original arrives for translation — technical condition of the computer file, issues with formatting, legibility, errors etc., which we could roughly summarize as problems with the source
- non-standard or otherwise cumbersome requirements, especially of doubtful rationality, which we could roughly summarize as problems with the requirements
- any combination of the two plus deadline or budget constraints
For context, notice now such complicated, problematic jobs have a tendency to arrive at the last minute and desperately need your attention — notably because nobody else wanted them (hint?), for example all your colleagues working in the same field and pair were 'too busy'. Often, those jobs also tend to involve someone else who was originally supposed to do the job but didn't. They also tend to involve other people not doing or not having done their job one way or the other. You know it when you see it.
Unlike the usual unprofitable job that you consider and reject after examining the specs at a leisurely pace, perhaps sitting back and sipping your tea slowly, the situation is much more dynamic when someone wants drop a hot potato in your lap; there is more pressure for you to accept, preferably as soon as possible, often without giving you too much information — precisely because if you had that information chances are you wouldn't accept the job.
Remember what you are told is only the tip of the iceberg. If they don't want to be bound by even that, then you are about to have a problem.
In other words, you run a serious risk of an extreme case of adverse selection. The situation is similar to insurance clients looking not so much for insurance cover for the future as for insurance bailout for the present. This is why insurance clients are required to disclose a whole lot of things before the policy is issued for them, and lying voids the policy.
You too need a client's lie or gross over- or understatement to void the agreement, at least regarding the fee and deadline. While getting compensated is one thing, you first of all need to avoid being set up for scapegoating when someone wants to outsource not the job itself but the responsibility for the failure.
My advice is to (0) outright skip the most risky jobs at all, and for those that (barely) fit within your comfort zone, not stop at just writing the most important terms and conditions down as usual. Instead, make sure you also (1) include all of the things the client said to talk you into accepting the job — as conditions of the job.
Next, (2) make all those things an explicit condition of the fee and the deadline. To be extra sure that you are protected — but also to be extra fair to your client, which is an important ethical consideration for any professional — (3) specify what what is likely, or especially what is certain, to happen if those things are not actually true, and (4) get the client to confirm, expressly and specifically.
Example (editing/revising assignment):
You are asked to check and edit 5000 words for the day after tomorrow for a specific fixed fee. They say you will receive the translation by tomorrow noon and the translation is going to be very good, just needing an extra pair of eyes and a little of your special touch here or there.
Step one: You make the delivery by tomorrow noon and the reasonably good quality an express promise by them and part of your agreement with them. For extra safety, you may want to stipulate that it has to be a complete translation without leaving parts of it for you to do from scratch, and that it will be too late for changes to the original.
Step two: You stipulate that the punctual delivery of the translation to you by noon tomorrow and the overall good quality, completeness and finality of their translation are explicit conditions of your fee and deadline.
Step three: You inform the client that sending the translation late will (or may) affect the schedule. A less than good quality or less than complete and final status of the translation will (or may) affect the schedule and also your fee (potentially up to the full translation fee). Rushing to meet the deadline, if the client chooses that option and you are available, will require such and such rush fee; the rush fee will be higher for any parts you need to retranslate.
Step four: Your client needs to at least tacitly accept all of the above (proceed with the order after being informed of all of it), and preferably state an unambiguous, clear confirmation.
For the record, someone who doesn't fuss about giving you that unambiguous, clear confirmation is very likely to be a responsible businessperson who simply happens to be in a bit of a tight spot. Chances are you don't need to worry too much.
Naturally, you could think of a lot of other examples, including the use of specific CAT tools, file formats and related settings, formatting and visuals and other things.
Obviously, you cannot walk just about every client through a lengthy routine of essentially confirming that the client isn't trying to dupe you. But you can insist on every brief or PO including a description of the circumstances with acknowledgement of any special issues that may (or will) affect the fee and deadline.
Your standard terms and conditions — which you need to display somewhere accessible and identify as binding and non-optional when ordering a translation from you — will take care of typical low and distant risks, but for high-risk clients and any clients who impose their own complicated T&Cs on you, you will need to go through this special routine more often and in more detail.
The goal is not only to improve your legal safety but also (a psychological fator) to drive it home that making all sorts of promises and assurances to get you to accept and then backing out of them but expecting you to live up to your side of the contract — which basically means bait and switch — is not an option. Just like in medicine, the best therapy is prevention.
Chances are you will lose some jobs this way, but it's up to you to decide if you really miss the risk.
Also, you need to be extra careful with those clients whose terms and conditions get out of their way to outlaw any sort of flexibility, adjustment or change and shift risks on you. Whether or not they can, the fact that they try should tell you something.
Last but not least, you don't owe it to any existing or potential client to become part of their toxic situation, including especially any toxic requirements or toxic originals or toxic translations.
You may be heartless if you don't help them at all, but you aren't a heartless person for not taking over their risks and liability — especially risks and liability of their own making — and this here not-so-subtle distinction is a key difference. Help means labour, organization or some other kind of specific assistance. It does not mean putting your head on the block for them so they can emerge unscathed.
Remember that desperate people, in desperate situations, will fight tooth and nail to claw their way out, and they will use all sorts of underhanded negotiation tactics, some of them quite dramatic and quite unfair. You will simply need to resist them. Be compassionate, but rely on conscience and principle for moral judgments, don't allow people to take advantage of your good heart and ethical manner to manipulate you into toxic deals.