I learned to side slip while flying gliders. The bulk of training gliders (certainly the K13 I learned on) don't have flaps. They do have airbrakes or spoilers, which will steepen the descent. However, if you've got it badly wrong and really need to steepen your approach (remember, a go 'round isn't an option) then a hearty side slip is the answer!
I haven't ever had any problems side slipping a Warrior (-151 or -161), but usually have the fuel pump on by the time I come to do it (especially true on final!) Has anyone out there had a problem, (fuel or otherwise) or is this the aviation version of an urban myth?
I usually slip to the left but only because it gives me a far better view. It so happens that the pitot is on the left wing (for J-T, the pitot is at about mid-span, just inboard of the aileron, and towards the rear of the wing).
If anyone has had a genuine problem (personally, please - not rehashed bar talk) please let us all know. I'd rather learn from your problem rather than experience it myself...
Pronto