Picturesque meant - he decided after careful observation of the scenerey that inspired Twoflower to use the word - that the landscape was horribly precipitous.  Quaint, when used to describe the occasional village through which they passed, meant fever-ridden and tumbledown.
Twoflower was a tourist, the first ever seen on the discworld.  Tourist, Rincewind had decided, mean 'idiot'.

Rincewind shivered.  He was not, of course, an atheist; on the Disc the gods dealt severely with atheists.  On the few occasions when he had some spare change he had always made a point of dropping a few coppers into a temple coffer, somewhere, on the principle that a man needed all the friends he could get.  But usually he didn't bother the Gods, and he hoped the Gods wouldn't bother him.  Life was quite complicated enough.