I hesitate to name many actors as truly all around bad. To me, most of the bad actors out there aren't really bad, they just make very bad role choices or just don't have enough range to do more than one specific thing. Adam Sandler, for example, is a purveyor of absolute trash.. but when in good roles like his part in Reign Over Me, he proves he's actually not a bad actor at all. Or Nic Cage. He's great at playing the neurotic off kilter guy. That's what he does and he does it extremely well. He can't do anything else convincingly but give him the right role (as in The Rock, for instance) and there's no one better. Keanu Reeves is the same. Poor range but there are some roles he's just perfect for.
Shia Lebeouf, however, is just eye gouginly bad. He either, at worst, ruins movies or, at best, makes you think of 50 other actors who could have done the same role better.
Shia Lebeouf, however, is just eye gouginly bad. He either, at worst, ruins movies or, at best, makes you think of 50 other actors who could have done the same role better.