For me, a hot cock is one that's on fire. J/k.

Seriously, a hot cock in my opinion would be about 7"-8.5" in length with a consistent thickness from base to head; topping off with a mushroom shaped head that's a little larger than the shaft. It can have a straight shaft, but they do look a little better to me with a slight curve in either direction.

Weighty and taut skin really turns me on. I like the "juicy" ones that don't really get hard, just more thick; but something about a truly hard dick that gets me crazy.

Lastly, a matching pair of thick, heavy balls totally seals the deal.