I find anything apart from Track number/title/artist/Album title to be unreliable. Album artist is handy if correct.
When I've asked for/looked for software that can sort by genre, or have a genre menu, its actually nothing to do with the genre that are in the tags, but the genre I would place them in. Ie basically its just a way of splitting up my database in managable chunks.
For example if I have loads of Dance tracks which to be honest I don't really want coming out at home, I could stick them all in a genre (or just mass tag them easily) so they only come up when I want.
Of course the same effect could be achieved by managing the database, or having mulitple databases, but I figure its much easier just using tags already present that would be no hassle to read. I hope....