The worst of it is, that while I notice typos or continuity errors with great ease, my grammer isn't the best. I can do the basic, and I notice the really bad stuff, but there has been many occassions where we both beta for another friend - I do the continuity/typos and (supposedly) the grammer and my then first friend will take what I've done and beta it again!
My only consolation is that I'm usually way better at the continuity!
Loriel