One of the lowest points of the team acting like complete idiots has to be in Season 12’s “Though the Heavens Fall”, where Chemo and Lori sit in the car acting like total morons stuffing their faces while crimes are committed mere yards away in the house they’re “surveilling”.
Actually, that episode is so bad that it ends up being quite laughably entertaining, albeit in all the wrong ways.

For me, the worst episodes are the ones that are horribly plotted, scripted, acted, the characters act stupid because the plot requires it, and they AREN’T laughably entertaining!