Pet peeve for the day: programs that don’t detect the currently selected default printer, but instead blythely use whatever they were using the last time they were fired up.
It’s not necessarily a bad behavior (I can see arguments for it), but … um … whatever I’ve specified as my default printer should be what I am shown as a default (or I should at least be warned about it).
Fortunately, the it usually just hits me as an inconvenience (it goes into the queue for my home printer, not my office printer, or vice versa), as opposed to a serious problem (it going into the queue for a public printer, not a confidential printer). But it’s still a PitA.