After the first season or so, they ran out of excuses to cover the presence of the camera crew.
Initially, they said that they were shooting a reality show where they’d get a chance to vote on the “candidate” (boss in disguise) to determine whether they should get the job/franchise, whatever.
But after the first season, someone would have to be pretty incredibly oblivious (or living under a rock) not to realize that the presence of a camera crew trailing someone meant it’s likely “Undercover Boss” doing the filming.
And it seems like the disguises have gotten worse not better each successive season. I mean, if someone is going to be doing physically taxing stuff where they’ll be sweating, don’t make things worse with ten tons of glued on hair, mustache, beard. Good grief.
It’s really laughable sometimes watching this poor guy sweat to death with his wig half falling off :)