I've not done much browsing around using categories, myself. I usually look primarily at the works of those I watch, and favorite based upon the basic feelings of the image. Occasionally a fetish that I'm not especially fond of will come up, and I will still favorite it because the artist did a great job of capturing happiness and love in the characters who are sharing the intimacy (or the character indulging him/herself).

I suppose the biggest theme I watch for is wet-and-messy, whether the art is tame or erotic, but there are only a very small number of artists who draw this theme. When I find one, I consider myself lucky. It's a shame there's no tag for it (yet).