Sometimes, a party to a negotiation will attempt to use an AbsentProxy (or some other external circumstance) as a constraint on the negotiation. For example, "we can't afford to pay you that much--we've just had a bad quarter", or "I'll get fired if I don't make my quota". If you hear that, one thing to do is to respond ThatsNotMyProblem--your only legitimate concern is to get the best deal for you. Certainly, the HR guy at a prospective employer, or the finance guy at the auto dealer, is going to be unconcerned with your financial situation.
(Plus, if the other party truly is in difficulty, then a) it might be better to walk away--no sense taking a job at a company headed towards bankruptcy, or b) this might give you an advantage if the other party is desparate).