EXCELLENT point.
A buddy came over the other day, we decided to do some drills. He is an accomplished competitive shooter. He only had his "under the seat" glock 19 and right out the gate on a cold, double bill drill his glock would not function. The trigger reset would hang-from .5 to 2.5 seconds and required manipulation to to get it to reset.
Took it apart, it was dirty-he had subscribed to the "never clean" method and because of the lube and grime, it had fuzz/lint with it from riding under the seat.
While I won't tell another man what to do/not do, I'd highly encourage folks to test fire and clean periodically.