I've noticed a definite restriction on advertising at NCAA tournament
games but not at any other games.  For example,
every year the CCHA tournament is held at Joe Louis arena in Detroit
which is also where the Red Wings play.  For this tournament, there is
no attempt to remove any advertisements from the boards, ice, seats,
beer cups, etc.  However, during the NCAA regional game (which for several
years was held about one week later in the same venue, often with the same
teams) no advertising was allowed including team posters and banners.  The
funny thing is the attendance for the NCAA tournament game was much lower
than that of the CCHA game.  Go figure.
 
-Matt