How would you handle

It can be uncomfortable to initiate a confrontation. It is even more difficult when the other person is an elder, one that we are traditionally encouraged to respect.
Tough situation for certain.
You could tell B/O Bob that he needs to CALL before he visits, but then the stinky bastard has your number.
You could close up the garage when he shows up and say that you have to get ready for some event. (Dinner/movie/miniature golf, etc) If he says he will join in....Oh crap, what then?
I suspect that you are polite and accommodating to him out of respect. He may be ignorant of your disgust. Many people are clueless and dumb as ****. They have to be hit in the face to get the point. I've known guys over the years that were unbelievably slow to take hints. They'd come around at the wrong time and stay too long. My Mother often said don't wear out your welcome and that has always stuck with me. I always call before I show up and I don't stay too long. I'm guessing that this unwashed loser isn't married, right?
As an aside to this....
I've had this ongoing fantasy about being able to temporarily jump into another person's body and live as them for awhile, just to see how they live. Sort of like walking a mile in their shoes. The thought of this often has me acting super aggressive when the person's normal demeanor is sweet and polite. I've thought about doing the opposite as well: Being nice to people that the "host" has alienated over the years to mend strained relationships.
Strange fantasy, yeah....But an interesting concept to me.
In your case, it might be fun to do the following:
B/O Bob walks up while you are in the garage working on the Dart.
"Hey, whatcha doin there? Hows about a hug?" Bob leans in, you step back.
"Hello, Bob....I was just wrapping up, I have to get going.", wiping your hands on your pants.
"Plans? Bob says Where are WE going tonight?" he says with a grin.
You roll your eyes. "Uhh, WE aren't going anywhere. I'm meeting some friends for dinner. Sorry, I have to go." B/O Bob isn't deterred.
"Rani, I'm hungry.... I could eat...." Bob smiles and anxiously awaits an invitation.
"Bob, you could do a lot of things....Bathe, use a stronger deodorant, learn to respect other people's time, visit someone else, get a girlfriend, take up chainsaw juggling or alligator wrestling, all sorts of things."
B/O Bob is standing there with a stupid look on his face. He says:
"So what are you trying to say?"

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