Originally Posted by
GUWonder
Whether someone here confirms it or not for their own travels, the fact of the situation is that people do travel on intra-Scengen flights with expired Schengen visas, expired residence stickers/cards or with passports having stamps that make it seem like they have been in the Schengen zone for more than 90 days within any 180 day period. If any or all of that is a problem during the course of intra-Schengen travel by air, it's a very infrequent problem for persons in such categories.
You're absolutely correct, but the opposite is also true (intra-Schengen flight: my sister was denied boarding because her Schengen-country passport (!) had expired three days earlier). I guess there are explicit rules somewhere, but a) there are strict check-in agents, b) there are laissez-faire check-in agents and, unfortunately, c) there are stupid check-in agents; in brief you'll hear all possible outcomes from travellers, frequent or not, who faced situations.