If a person has bad personal hygiene, they are more likely to have bad body odor almost all the time.
Some people sweat more than others, which usually has a bad smell.
If a person doesn't change and wash their clothes often, they will have a bad smell.
Some fabrics increase and worsen the smell of sweat, which could be one reason behind some people's constant bad smell.
Some foods worsen the smell of sweat and make some people smell very badly such as garlic, onions and spicy food.
People who have active routines that require them to do a lot of grunt work may smell worse than others.
Some health conditions can result in a bad body odor such as being overweight and having diabetes.
Some people prefer not to use perfumes or deodorants, which often results in bad body odor.
If a person lives in an unclean environment, it is very likely that their bodies will smell like it.
In areas where the climate is hot most of the time, it may result in some people having a bad smell due to sweating all day.
Underarm hair worsens the smell of sweat in most cases. Periodically removing or trimming it can help the problem.
Some people have more bacteria on their skin which worsens the smell of sweat.