Not necessarily true. Some people honestly just can't smell the odor. This tends to be family members and close friends, probably because they are constantly exposed to the odor and their nose gets accustomed. The MEBO website has some possible explanations I think. But,I agree that sometimes people just lie to your face even though you've SEEN them react to you before. :/ There was a youtube vid I saw once by a couple of pranksters that showed that asking about bad smells doesn't always get the most honest response (but the people being asked here were total strangers). http://www.youtube.com/watch?v=3oErUYZgjxM
That being said, I think it is likely the OP has an odor about him (judging from the reactions he has seen), but improbable that his close friends and family are lying to him (though certainly not impossible, just going off my own experience).