Icing . . . .
Re the taxiing in hot air argument.
Having regularly flown numerous VW powered aircraft I can't think of one which had an air filter on the cold air supply. Most took the cold air from inside the cowlings, so it wasn't true cold air in every case. The hot air comes from a muff on the exhaust(s) which are generally outside the cowlings. So taxiing in hot air means you may pick up slightly more debris than by using cold air ! Applying hot air well before closing the throttle is good advice. In humid conditions it's a good idea to use slightly higher power settings to generate more heat in the exhaust system, also, icing is more likely to occur at small throttle openings.
I've never had a VW carb-ice problem, but other bits of "excitement", yes !