The Gimli Glider (AC 767 that ran out of fuel at FL330) was side-slipped with no problems.
As for the terminology, in Canada we're taught 3 types of slips:
Sideslip- used for crosswind approaches, low wing into wind with opposite rudder to keep the nose straight.
Forward slip- used when you need to fly like a brick. Low wing into wind, opposite rudder to keep nose pointed to side with high wing, nose way down to maintain speed. Airflow hitting side of fuselage creates enormous drag.
Slipping turn- rudder opposite direction of turn. Great to have when too high turning base to final.
Never had a problem slipping 172, just don't do it with flaps greater than 20 degrees. I don't like how the 172 handles with full flaps anyway and I find that the buffeting spooks the pax.