I thought the acting was great when Crude Fat Guy said to Joan “Let’s see 'em”. When he says that, it establishes that he’s such a cretin there is no way she can fantasize her way out of what she’s doing (i.e. it’s not something she can later pass off as a ‘I might have slept with him anyway if I was drunk and he was cute’, this is prostitution plain and simple.)
OTOH, Pete had a point when he said many of us have made unwise or embarrassing decisions that led to one night stands for free. At least hers has the potential to set her up for life for what is at worst an evening of her time with a crude and clumsy lover. Keep in mind she got nothing when her husband basically raped her at work; this time she was at least largely in control, and she really was not required to sleep with him- she would not have lost her job had she refused. (It would be a good IMHO thread- would you prostitute yourself in an "indecent proposal’ situation with a potentially huge reward; I won’t start it but hopefully someone will.)
Do you think Don even associated Peggy leaving with his throwing money in her face? He gets flustered sometimes, but that was such a dick move that I’m surprised he didn’t apologize for it later on his own. (I wondered if it was to contrast her and Joan by the writers- both women make a major life decision when money is thrown in their face, one figurative and one literal.)