Banners that convert: with text or without?

You know those custom banners made by affiliates that are basically just a photo of a hot guy or scene from a sponsor? They don’t have any text or logo that indicates what site the photo is from or where the surfer will be taken if they click on it. Sometimes these banners may include generic text like “Hard Naked Men” or “Hot Gay Sex”, etc. but the surfer has to click on them to be taken to a gallery or site where the sponsor is actually identified.

Do you think these banners are more effective than the traditional banner that has a site name on it? I was thinking that if a banner has the sponsors name or logo and the surfer was already a member or a past member of the site they probably would not click it. Without the name/logo they might.

The best examples of the kind of banners I’m describing can be found on Adam4Adam, but I’ve seen them on many other sites too. I suppose this practice probably even dates back to TGP sites that just had photos that took surfers to galleries… the thumbs had no text on them.