I’ve never stayed in a dorm, but my parents (in their late 60’s at the time) once drove around Sweden at the height of the tourist season with no plans and no reservations. They found hotel rooms by stopping at “tourist information” in each city and ended up in a uni dorm at least once. They thought it was great.

I stayed at Institute St. Sebastian in Salzburg Austria in June. It is a dorm for female college students. They rent the extra beds out to travelers. I had a 2 bed dorm, good lockers, with sheets, blankets, towel, and breakfast for 19 euro per night. Nice clean place, not a party hostel. Good location too. Book directly with them through email. Here is a link to their web site.
http://www.st-sebast…

Stayed in a Uni dorm in Budapest which turns into a hostel in the summer. Was a huge place with about 7 floors. Was very cheap and fairly comfortable. Although would not fancy staying in them for a full Uni year a bit small for that.