King Rufus and the nosey drive-by's

 
We have had several instances where a certain vehicle keeps driving by, and sometimes pulls into my driveway and "admires" Rufus. He has actually asked me a couple questions.... I don't know what is up with this. At first I thought it was like a lot of people, just shock value stuff, like what's he weigh, how much does he eat, is he mean, blah blah blah..
 
Now I am wondering if I have encountered a potential dog theif. Mastiff puppies very often cost more than a thousand bucks, and Rufus is much larger than the typical breed standard, so this really worries me.
He NEVER barks. NEVER. He's too lazy, I guess.
But when these people drive by, he goes CRAZY. Dog intuition?