Usually when I'm pouring I've got 5-6 molds going so I don't always see any messed up ones. I see them when I get to the trimming of the sprues.

I trim the sprues and keep em all sorted by size and style. Misformed ones go in a pile and it all depends on how bad they came out. Last time I poured before we moved I had 26 and just cut all the collars off. That solved the whole problem.

Fatman