As far as overtime, specifically, is concerned, well, I have written about that before.   If your contract says (for example) that you will be paid time-and-a-half for overtime, then you might (or, might not) decide to accept a little bit of it.   If it does not, then you are simply being asked to work a bunch of hours that you are not getting paid for, and you obviously know what you should say in response to such an absurd proposition.   (“No tickee, no shirtee...”   “Not only ‘No,’ but ...”)

But bear in mind:   you do have to say it, one way or the other.   As they say in those in-flight magazines, “in business, you don’t get what you deserve – you get what you negotiate.”   The mere fact that someone asks you to say “yes,” does not mean that you are obliged to do so.   The mere fact that a company puts such a question into the initial dialogue is certainly a red-flag sign to me, because, as a businessman, I know that the rule of the game must be “you get what you pay for, but you must pay for what you get.”

If a prospective client (direct or indirect) tips me off that he considers extra unpaid hours to be de rigeur, I immediately want to know, “why?”   My response is usually something along these lines:   “I understand that this project is seriously off-course right now, but I fully expect to be able to set things on a much more even keel in very short order, such that the overtime expenses will be eliminated altogether, not just for me but for the entire project.”   (You are not only indicating your refusal to accept overtime without pay, but you are turning it into a positive reinforcement of your value-proposition:   a professional as stunningly capable as you are, doesn’t find it necessary to work overtime.)   If you are dealing through a contract-agency that is not willing to make statements like that one, perhaps you need to reconsider.   If you place yourself in a situation that needs negotiation, but you have no bargaining power, that can be a serious matter.   You have to go in, if you do, with eyes wide open.   Some companies hate to negotiate so much that they will suck-up and say anything they think their client wants to hear.   (Goody for them, but do not get caught in the middle of that.)   If you have no bargaining power, you will find yourself obligated to fulfill in good faith whatever working arrangement your employer did (or didn’t) bargain for, and you will have little or no power to change it.   Caveat Consultant...

A project that is in trouble, but that is working its way out of those troubles and that is determined to get out and stay out, is one thing.   A project that thinks it has found a wonderful way to save on direct-labor expenses, is quite another.   Sometimes you have to follow your gut on these things, knowing that you might be turning down a gig that will pay your rent for the next forty-leven years (or that might be six months of unmitigated hell), and that you might never know for sure if you did or did not make the right decision.

Pay attention even to trifles.
– The Art of War