As a standard norm, I would agree. But there are many exceptions, and who is anybody to say it's wrong if both parties like it? It might sound "perverse" to some, but I heard of a couple where the wife was very attractive and would give her husband sex only if he regularly completed a long list of household chores. Strangely enough, he got turned on by her having this power over him.
In their case, you could say it was "barter" itself that was the spice.
I wouldn't mind playing like this. Sounds like fun.
