There are many ways possible to perform such illegal actions. To burn a graphics collection on a cd and sell this is only one possibility. There are many more less evident ways such as recolor the graphics (passing them through a color filter), or recolor them pixelwise. And redistribute or resell the modified version. Another way is offering them as preinstalled themes in a paid hosting or forum service.
And what if they are used on another profit site (not related to webhosting or forum hosting)? Isn't this also kind of reselling? Namely you sell your service with the aid of that graphics work so implicitely you resell a piece of the theme...
I can imagine even more methods. For me that question is not so easy as it seems to be for you.
