After being recommended by Rough Guides, as a gay man, I visited OHM. I was charged 2.000 ptas entry, and 800 ptsa for a beer, and over 70% of people were hetrosexual.
Now, I have absolutely no problem with that, but I like gay bars. And gays bars are what they are! OHM is an overpriced hetro bar\club. I have no idea why it was included in the gay section of Rough Guides and, in my opinion, should be taken out.
I live in Amsterdam where gay bars are gay bars, and that's what I like, and expect. Not dark rooms or the like, I'm not into that. OHM is a HETRO disco, and should not be classed as gay. Compare OHM with, for example, the Exit or the Trut, from Amsterdam, if possible.
If you're looking for a good club in Madrid my suggestion is to avoid OHM! Arrogant, advantage taking doorman, overpriced beers, and a non-gay atmosphere. Also very hard to find - below a cinema on the Gran Via, and not obviously on Plaza del Callao.

No