I'm a total lurker on gay dating sites. My favorite is
DudesNude because they let you search and look at pictures without even having an account, never mind paying a monthly fee like a lot of them want. It's also totally NSFW and a lot of people post naked pics in their profiles. I also like lurking on another one, called connexion.org, it's also cheapskate friendly and doesn't constantly try to get you to buy a subscription.