Okay so I was just wondering if it is a possible behaviour, maybe some of you guys do it, but if a guy 'might' be interested in you, do you find that he will talk less in a way.

This could totally just be me and completely overthought but generally when I talk to a straight guy conversations are easy and you just talk about whatever random crap. Then when it comes to certain guys every now and then, they'll be smiling but just don't say much or get quiet.

I only say this because I'm trying to develop a 'gaydar' of some sort for my particular circumstance where I try sussing out without going to gay bars and clubs etc as even the normal clubs and bars don't appeal to me that greatly.

I know it could simply be that the person is just naturally introverted (which I am naturally inclined that way too but I can be extroverted if necessary) hence me probably overthinking but I thought maybe it's a possibility.
In my head I'm thinking, 'well if they don't want to talk to me they'll just go talk to someone else' but they'll just stay and smile and make small random talk that kind of goes nowhere in a sense. Like they'll say something that you can't really respond to.

It's not that the awkward silent moment is annoying and I try make them feel as comfortable in the conversation as I can because it's not like nerds (such as I) have the best time in conversations naturally but every now and then (as in more often than a blue moon, but not that common either) I 'think' (keyword 'think') they look my way and hover near-ish me and then if we do have a conversation it's silent in that not much is said and so I'll think that they'll go away but they stay for a bit and smile.

As I said before I'm trying to set the foundation of a possible 'gaydar' since mine is probably poor to non-existant and its just something I've kind of noticed.
I am totally happy to accept if this is completely misread and I'm just wrong.

Sorry for all the weird analogies, examples and overkill of bracketed comments by the way.