I don't delete them in camera for the same reason. Better to grab another card or two instead
When I get them back to a computer, I generally have at least two iterative passes through photos to decide whether to delete.
1. Delete the obviously bad ones - blurred etc.
2. Next time round try a 60 sec fix, e.g. correcting tone, exposure, cropping, straightening. If still no good then I'll delete it.