My common complaint is why must some tourists walk around Taormina wear just their bikinis? No t-shirts, too tight speedos and I'm talking about the ancient hilltop medieval town, not down by the sea! Firstly, it is disrespectful and secondly, the medieval town is 700m above sea level, meaning that from the beach to the hill top town you have 700m worth of time to get dressed before walking into shops and even restaurants dressed (or should I say not dressed) like this.
The other day I felt like cheering aloud as I saw a polizia on the Corso Umberto, our main street, stopping these fashion offenders and asking them to cover up. Not content with a 'yes' the police man stood there and watched while the many embarrassed people put on t-shirts, shorts, shoes - you name it.
I have so many entertaining stories about the customers I work with...I had a complaint the other day that Stromboli (one of the Aeolian Islands, which is also an active volcano) did not erupt. We sell excursions to this island and tell people most of the time they should see some form of eruption or explosion from the volcano. Obviously not being mother nature I cannot guarantee the eruptions. These guests made an official complaint, asking for a full refund as they saw no activity from the volcano that night.
The other night a customer complained that the antipasto is always cold, there were no potatoes on the menu and that at many of the restaurant staff cannot speak English. Sorry - but what country are you visiting again?