Really depends on the port of entry & the prevailing 'tudes there. DTW is the worst, never hassled for short stays returning thru ATL, "worst" that's happened at EWR is that they X-Rayed our baggage (no extra questions, probably < 60 seconds added inconvience).

My perspective may be a little different from yours since they have to let me back into my own country. During one idiotic secondary at DTW I just got fed up with the repeated questions and replied something to the effect of "I already answered that, just inspect the luggage & get it over with". He elected to end the secondary at that point.

They are supposed to provide you with feedback cards for such secondaries.