I've always believed that most people who have bad BO do so because they don't change their clothing often enough. This leaves aside those few (?) unfortunates who have some sort of biochemical imbalance. Nevertheless, in order to avoid an anti-social pong it's probably best to both bathe regularly (like once a day) and to change clothes regularly (ditto).
I once worked with a bloke who had absolutely dreadful BO - you could smell where he'd been by the sort of trail that he left hanging in the air behind him. He was so bad that he was often the sole topic of conversation in the workplace. The personnel department had a few discrete words with him but he just ignored them. He got very close to getting fired but, luckily, left of his own accord. My view was that this person was an anti-social git and deserved to be fired!