When it comes to porn (amateur or otherwise), you can be as picky as you damn want. Who will you blow your load to? Who's worth it? And most importantly, if someone cums to a guy's picture, does the guy psychically sense it as a sort of mental tickle or ego boost?
Yeah, that would be fucking weird if guys did feel it. Sort of the opposite of that "Every time you masturbate, G-d kills a kitten" meme. Because we all know, it's really "Every time Mike Huckabee masturbates, he kills a kitten because that's what gets him off." Allegedly.
And aren't you glad you live somewhere you have freedom of porn choice? Imagine some dictator choosing your porn for you. Making you masturbate to whatever they choose. They might make you jack off to golf tournaments. Unless you have a fetish for ugly pants and (imported) beer guts, you'd be in trouble.
So I'm fully expecting you to compliment guys with a good-natured "You're totally cumworthy, fella." Or just say it wordlessly, by ejaculating on his chest or thigh or ass or wherever he'll take it. Probably make sure he knows you exist at least a good 10 seconds before you ejaculate. On the off chance that he's not into it. Like maybe he's worried about getting cum out of his new linen pants. In which case, make a cum date for the next week by which time he'll have gotten a dozen other loads on the pants anyhow because you're not the only one who thinks he's cumworthy.
Nick Capra, for one, has decided that Mike De Marko is totally cumworthy. So he fucks him and cums on him. A natural reaction.