When a guy acts cool towards you, does he mean it(uninterested in you) or simply he j

lol no no, as soon as I enter conversation I tend to smile a lot more and laugh. I keep a straight face only when I'm just walking around/on my own/stuck on the tube etc. (although usually I am genuinely stressed/pissed off when cramped on the tube (6'1" + tube in rush hour just does not go).

I know the last post was over 3 weeks but ah well; here goes.

Just because a guy does not smile back at you does not mean he doesn't like you.
I work at my big local super market and meet possibly hundreds of girls a day, from the ugly to the extreme hot girls to teenagers to 20+ years old. Personally, I never knew I was very good-looking but almost every single girl gives me quadruple glances, staring me down or smiling at me. Eye contact all the time, can hardly do my job!

For some unknown reason no matter how good-looking the girl is I just cannot smile back for some reason! Its very annoying and I don't know why! I try but can usually only give a small smirk! It depends what mood I'm in as well. I'm a friendly and talkative-ish guy but nevertheless.... no smiles!
I get angry at myself because I'm positive girls get annoyed at me for not smiling back and I feel guilty afterwards!

What I'm trying to say is, 99% chance that its a problem on the guys side that hes not smiling back!
Hopefully this helped some people!

EDIT:

I'm 17 years old BTW.