If we should have to give credit to the stuff we pay for, I think it is only right that we are paid for advertising it. I also think that these rules should be posted in big block letters on the product page besides the readme so everyone knows that is what they need to do before they buy.

I do post what modeling and texturing and lighting and so on that I do. I rarely use free stuff, to much hassel keeping track of readmes,if there is one. If that's not clear enough fo those that read my credits, too bad.