There's a reason both umpires enter the same dugout and inspect the bats together: it allows the umpires to consult each other and build a consensus on whether to allow certain bats that may be questionable. The umpiring team may then stand together after making a decision on whether a specific bat is to not be allowed into the game.
That being said, if the umpiring team finds a bat that, upon examination, raises sufficient suspicion, they may certainly restrict its use in the game. Umpires should not "go looking" for trouble in this regard, but when trouble is found, it must be dealt with. If the bat, for example, has any of the following characteristics, then the umpiring crew should be compelled to restrict its use:
- obvious pry marks around the end cap
- visible adhesive coming from the end cap
- raised decals
- paint covering the end cap
- the incorrect end cap
- Easton bats with the "Easton" stamp not properly lined up across barrel and end cap
Again, I reiterate that an
umpiring crew should not look for trouble, but when trouble is encountered during the pre-game equipment inspection, it should not be overlooked. They should absolutely back each other in these matters.