Yeh like others have said if you feel really hot and kinda have a mexican wave of heat going from you toes to your head..it's likely you are blushing although i guess it depends a lot on the persons skin type, some people just have really blushable faces?
With me people seem to notice it a lot, you can tell by their expression really, a kinda grinning...what's he doing? face. That and the 'oh your quite a blusher aren't you!' comments lol. Lucky i've actually come to live with it so i can shrug them off but a few years ago i woulda just froze up.
It's pretty much the main thing that made me so shy as it happened with everyone as all i'd be thinking is, shit...im gonna go red. So it basically just caused really intense humilation, kinda like when ever i had to talk to someone, i would be on the same level as standing in front of them nekkid....and i'm not exactly a nudist...