The downside is they can sting repeatedly...As I learned once when I swatted at one and it got caught under my watchband...
Supposedly, yellow jackets are fairly docile and not easily riled unless their nest has been disturbed before. They are also supposed to be more or less beneficial as they prey on many destructive insects, but the hazard they pose to unsuspecting people and pets more than outweighs their benefit, if you ask me.
I was pulling weeds when the yellow jackets got me. Good for a 911 call. Couldn't use my hand or even lower my arm for better than a week afterward. You'd think that would get me out of weed pulling duty, but no such luck.
Carpenter Bees?
Male Carpenter Bees are the ones that hover near nests, trying to intimidate you. However, males do not have a stinger. Females have a stinger, but they usually stay in their nest. If provoked, they will sting, but that is rare.