The use of projective tests to assess personality is highly controversial. Many people question it's reliability and validity because of the nature of the test. A projective test is one that presents ambiguous stimuli such as that in the Rorschach Inkblot test to the examinee who has to say what they see.
Take a look at the image above. What do you see? Is it a lady carrying a basket on her head, a very mean looking face, or is it something else? Be careful of the answer you give to the examiner. Any specific detail you focus on is supposedly associated with a personality trait. In the Lilienfeld textbook it gives two examples: if you focused on the tiny details in the inkblots you have many obsessive-compulsive tendencies, and if you focused on the color in the inkblots you are said to be emotional. Just because you see the smaller things in the picture doesn't mean you have obsessive compulsive tendencies, you may have been unable to focus on other things because the picture is so ambiguous that you can't make any other kind of sense of it. There could be other rival hypothesis to explain the reason you saw a certain image in the inkblots. One reason could be influences from earlier in the day, like seeing a monkey on tv and picturing that same monkey in the inkblots in front of you. The Lilienfeld text points out that there are very few results which are replicated between Rorschach scores and mental disorders. It also says the test-retest reliabilities are unkown. The associations given from each response may have some surface plausibility, but that doesn't mean it's the cause of the response; a mistake in correlation vs causation.
Overall, to me the Rorschach test isn't very reliable and for each answer the examiner gives an interpretation to, there are many other simpler reasons the subject gave that specific response. These tests don't have test-retest reliability, and the lack of evidence for its incremental validity.(Lilienfeld)
Chapter 14 Lilienfeld Psychology textbook