And will it make you smell better if you eat no onions, shallots, garlic, or leeks?

Subjective: The question is whether you want to give up an enjoyable element of dining to relieve bad breath when a toothbrush or mouthwash would be effective. As for general odor, people who eat lots and lots of garlic will develop a body odor which is distinct, as anyone who has lived in korea will tell you, but whether this is distasteful is a subjective opinion.