There's lots of really awful movies out there that are sort of obvious choices here (such as Plan 9 From outer Space for instance), but for me, there's a couple movies that I've seen over the years that sort of stood out as being just so boring, derivative and just completely bland but also had some big names and actual "real film" production behind them.
this one...
and this one...
just utterly, annoyingly forgettable movies. Air America had the added unlikeable quality of trying to capture a bit of the Good Morning Vietnam vibe. Gibson's character was just so stupid and ridiculous.
lol...just looking at those images causes an almost existential boredom within me!