Responses like "Sometimes I let people take advantage of me", or "I take criticism personally" are not good answers. "I'm too honest" or "I work too hard", even if they believe you, make you sound like you'll be irritating to be around or you'll burn out.
Instead, say something like, "My biggest weakness with regards to this job is, I have no experience with [company's database platform]" or "I don't have much knowledge about [single specific aspect of job] yet, so it would take me some time to learn."