Yes the German reception and crowds shocked me too. I do think Charles is benefitting at the moment from being in his first year as King, meaning all of his visits are technically firsts. First state visit as King, first maundy service as King, first trip to X,Y,Z as King, so there's a bit more to it and gives a historical incentive to turn out and see him. I don't know if he was to say visit Germany again in 7 years, would he get the same reaction?
That being said I do think Charles is actually much more popular than the press and Diana stans would have you believe. Everyone who has met him seems to sing his praises and he always gets a good turnout at engagements etc. The press picked their side in the battle of the Wales's and chose to paint Charles as the cold husband and father etc and the Diana cohort will never be swayed, but amongst the general public I gather he's actaully rather well liked, his tributes to "mummy" have helped too of course