same experiences here. if you are aware of this and if you are not confused to the point of desperation, you can still learn by it.
i found www.javaranch.com/maha
listing with comments a very good source for guaging mocks for what i have seen. maha is quite polite to mock authors (who did put up lots of efforts and are giving their services for free), but if you are short of time, you should focus on what maha considers very good, cannot miss, etc.