If you shop around for a loan, I understand it can lower your score due to having several inquiries on record.
Although several inquiries at the same time, for the same sort of thing, are obviously not a sign of trouble but a sign of shopping around. I read somewhere that the shopping-around issue doesn't trouble your score much, because they take into account a group of inquiries close in time as being credit-shopping. If, however, you inquire from time to time, or are constantly poking around for more credit, that would count against your score.
There really should be more transparency in the process, though. You heard that, I read this - who can say for sure what's in their scoring programs?