to be fair its a ymmv game. i wouldnt blame heather if she doesnt feel comfortable to guarantee you this service with her girls. couple of them just went for it without up charging, because obviously they are here for the money.
however, i had an experience with a girl from bunz who i met many times before. she was giving me a good bj and all of the sudden she said i want to rim you. shit i was so excited and i just said of course hon and enjoyed it. but what killed the mood was right after that round she told me now u owe me $80. oh boy that felt so wrong, but again i should know better haha. paid it no problem, but i lost all my interest with her. so i never go back to see her again.