I tell the truth and I do fairly well!
You only have something to worry about if you're a psychopath ;) The majority of these tests are not designed to elicit the responses that you expect and lying just skews the results (for good or worse--you have about an equal chance of getting employment from lying then you do from getting employment form telling the truth)!
If you have any concern about gaining employment from psychological analysis I would seek a trained professional to elicit a test for you and give you some feedback. The written feedback I have gotten from tests I undertook was pretty good (and in my opinion relatively accurate).
I found the following particularly entertaining (albeit true) from the Macquarie group (SHL testing):