The best course to follow: Don't comment on anyone else's gun unless they ask for your opinion.
So, not even a "Man alive, that is a beautiful, high condition Mossberg!"?
Stan, a few months ago I bought my daughter a nice high condition Mossberg Pump shotgun as a house cleaning tool for unwanted miscreants. It even has a black synthetic stock, and despite being in perfect condition, it is less beautiful than a pit bulldog. It also has a worse bite than a pit bulldog. It doesn't eat as much as a pit bulldog, and unlike a pit bulldog, it will not mistake the mail-man or meter reader for a burglar or home invader. A pit bulldog has a menacing bark, but I think the distinct sound a pump shotgun makes when racking a shell into the chamber is even more likely to make an intruder piss their pants and run for the hills.
That's something our doubles aren't quite so good at.