Is it best to play a well established opening, or play randomly to dirupt your opponents set openings?
yes you are right
Play good moves that you understand.
Playing bad moves just because they aren't well known doesn't do much to disrupt the opponent, it just helps them.
Playing well known moves that you don't understand is likely to get you into trouble the moment your opponent does something unexpected.
Is it best to play a well established opening, or play randomly to dirupt your opponents set openings?