A smart circle is one where, for example, you gain enough height in thirty seconds to glide for several minutes. Another is the mile-wide exploratory turn in wave, drifting downwind into stronger lift while exploring laterally for even more. Or how about a quick circle just before entering the landing pattern to check for unannounced traffic? That’s pretty smart too.
Dumb circles? We see them all the time. Such as circling where you thought there might be lift even when there’s no actual evidence; circling where there was lift, long after either you lost it or it climbed away and left you; circling in wave when that’s certain to drift you downwind of the good stuff into certain trouble. And oh yes, circling and staring at your panel while other pilots are flying by you on their downwind legs.
Fact is, there are zillions more dumb things we can do than smart things, in the air as on the ground. Our job is to sort out these options and leave at least some of the dumb ones undone!