Honestly, it depends on the cock and the composition of the picture.
I could do without the thousands of generic, ultra close up pics of some hairy knuckled guy gripping his tool for the camera. How the hell is that sexy?
I have seen a few on here, though that have made me take a second look (& sometimes a third...& a fourth...&...) because they were presented in an artful or seductive way, not just as an object jammed into a lens.
i don't love the unimaginative shots from the picture-taker's point of view, looking down at his erect cock and the three weeks' worth of dirty laundry and Doritos bags on his floor (srsly? if you're going to take pictures that show your home, pick up first).
but i do love a well-taken picture of a hard cock, absolutely.
it doesn't have to be part of a tease, or a stolen glimpse.
I can take them or leave them. And you're right, when it's that close up, fist shot with computer cords and dirty socks in the background I'd rather leave it. Really there isn't often I'd opt to take them I guess. I prefer the sound of a man moaning as he jacks off to picture of it.