Filler is such a broad term ;-;. Sometimes filler is a one off episode, othertimes it's a string of episodes, sometimes its an entires 30 arc series.
To me, filer is only bad if it contradicts or interrupts the main canon arcs (ie, some of Bleach's filler arcs). One off filler episodes are easily skipped, I normally avoid the silly ones, but otherwise just sit back and relax! It doesn't really matter if it's not in the manga you read two years ago, as long as it's interesting/entertaining and doesn't clash in anyway :).
To me, filer is only bad if it contradicts or interrupts the main canon arcs (ie, some of Bleach's filler arcs). One off filler episodes are easily skipped, I normally avoid the silly ones, but otherwise just sit back and relax! It doesn't really matter if it's not in the manga you read two years ago, as long as it's interesting/entertaining and doesn't clash in anyway :).