If you aren't attracted to her, you can tell your friend that Adaisychain's personal opinion is just this:

"If in order to sleep with a woman you have to give a false impression, lie, or mislead a person in any way, it is wrong."

If you aren't attracted to her, and she thinks you are, she has a false impression. She might just want your ass or something if you're a real hottie ((unggh, sounds like it, she smokes good weed with you when you fuck her!!!)) in which case she doesn't care if you're attracted to her. In this case you are now a man whore accepting weed as payment.

Are you a man-weed-whore?

Would you have sex with me for really good crack? C'mon, I'm a 17 year old boy, but I'd pay you with a shitload of the best crack. Over here in this alley.

Basic principles are all the same.

You are no better then a crack whore.