Sure, when I see a hot man I'll think some lusty nasty thoughts - I think that's rather normal for a red-blooded gay man.
Do I act on it? No. What am I going to do-jump him?
I can think of a couple of times when the sight and smell of a guy got my juices flowing.
When I was working at the YMCA I was showing a new member how to use the equipment (gym equipment) and he was on the arm curl machine, and I put my hands on his shoulders to hold them down to show the difference it made. As soon as I touched his damp skin and got a whiff of his sweat, I sprung an instant erection. I wasn't evening thinking about sex, even though he was an attractive guy. I was being professional, but the smell and touch just set me off. I tried to hide my excitement until I could settle down.
Another time I was at a gay event, summer, a guy was sitting close by, wearing a tank top, and he lifted his arms placing his hands behind his head. I could smell his scent, see his furry pits, and I was immediately horny. I know some guys are grossed out by a man's pit smell, but at that time it brought out an immediate response in me. Pheremones? Maybe. Lust? Yup. Didn't do anything, just enjoyed the sight and smell.