How to gently remind my roommate that he stinks?

Maybe I can't be tactful. I used to think that euphemism was a kind of wisdom. Later, because the opposite person didn't call, didn't have wisdom and couldn't get the correct number, many things couldn't be done. I remember my former boss, of course, a friend of mine. His mouth smells a little. I'll tell him directly that your speech has a little bad breath. I suggest you put foam 1 minute in your mouth after brushing your teeth, and then rinse your mouth. Very effective. Because I think if he is a person with very strong self-esteem, his foot odor may be just a trivial matter, so we will be together for a long time in the future. Everybody be careful? You can say it directly, but you must have suggestions. Otherwise, you are looking for trouble, so how to put it mildly? I think the landlord thinks too much, and I don't think it's necessary to pay so much attention. Some people are endowed with wisdom by God, but he has an umbrella, and he doesn't feel euphemism at all. So, uh. ...