I'd have to agree with everyone else that the Cliff's books were a bit overkill on the verbal section. I believe that the difficulty of the vocabulary on the PCAT is very similar to the SAT - all the words are words you probably have encountered at some point throughout high school and college. The key is being able to make word associations quickly and recognizing traps.
For example, if they give you blacksmith and anvil, the main difficulty in the question would be finding the common link between the two items - the blacksmith uses an anvil in his work. The words themselves are not particularly difficult.
Most likely, there will be words you will not know on the actual PCAT, and in those instances, you should try your best to determine a relationship between the words. However, don't overlook the seemingly 'easy' questions, with simple words - you need to get as many questions right as possible. Hope this helps!