Some people should know better. Such as the lawyer who was busted by the BATF for buying a silenced weapon from a convicted drug dealer.
No, I'm not kidding.
Once upon a time ago, about the time I was posting the ASCII text versions of The Resister on Usenet, I bought a AK-47 chambered in 5.56 NATO. It had the thumb hole stock mandated at the time by our neo-soviet masters in Washington. As a former combat rifleman I took it upon myself to properly zero in the sights on the weapon. As I was doing this at the Moon Valley range down in Eden Prairie I was rudely interrupted.
It appeared that a scraggly young man wanted to sell me a folding stock for the AK-47. I said no. He repeated his offer. I repeated my refusal. Eventually he got the point.
First, I actually had no interest in a folding stock for the rifle. The folding stock for the Ak-47 series rifle is copied from the MP-38/MP-40 series machine pistols issued by the Wehrmacht. They are inherently unstable and were used both by the Wehrmacht and the Soviets to shorten the weapon for carriage within an aircraft or armored vehicle. An acceptable tradeoff for them, but not for me.
Second. folding stocks at the time were illegal. I was not about to ruin a weapon by installing an inferior stock simply for the sake of disobeying our self appointed masters. The proper way to deal with a master is to air out his head.
By his demeanor and his insistence on selling the stock to my unwilling self I concluded that this fellow was a stooge for the BATF. I refused to fall into the trap.
A simple bit of common sense can go a long way.