Do people that smell bad know that they smell bad?

Genuine question.

I'm not the most hygienic person out there, but I do know that I don't want to make other people uncomfortable or gag when they're sitting next to me. However, I have seen people close to me and passerbys that stench....the kind of stench that makes you physically gag and turn around.

This question surface in my mind after watching a movie with a friend last night. When the movie was over and she got up, there was this awful stench that made me physically turned around and put the blanket over my face. She thought that I was tired and said goodnight to me, but I was really turned off by it. After she left the smell was still there hours later and was not gone until I spray odor removing spray many many times. This is not the first time that I've been turned off by her scent. I think that she may have hygiene issues. I loved hanging out with her and she has been my friend for 6 years, but it makes me wonder if she notice that she sometimes smells funky?

I personally smell myself throughout the day to make sure that I don't smell off. I've had issues in the past where I stank very quickly/easily because I sweat so much. But I have been able to manage that more now. however I still smell check myself because I remember how awful I smelled back then. If I could smell myself then surely others can too and it would be 10x worse for them...that was my logic.

Does anyone have any advice or experiences to share?

Thanks