Correcting typos in the catalogue can make me feel a bit of aggression, or frustration at least. The actual error can be so small -- a repeated letter, a missing one, a swapped letter -- that the human eye passes right by it. In longer bibliographic records, they can be almost impossible to spot, even if you're sure that record contains your typo.
One trick we've used at my library is to view the record from the public side in a web browser, then type CTRL-f to bring up the "Find" command, and type the potential error in.
Of course, this only helps if you're working with a prescribed list of typos and know the errors you're looking for. If you're not, then I wish you luck, and try not to hit, punch, or kick your computer, or you'll never locate agression*, a high probability typo.
(Aggressive cat photo from Wikimedia Commons)