In addition, the candidate's enthusiasm after the interview will fade to some extent. Companies that can't come close to meeting someone's salary demands sometimes read the candidate a laundry list of his shortcomings to justify a lower salary. People do some strange things when they're trying to make a good impression. Another bad idea is intentionally lowballing on the first offer knowing well it will not be acceptable. The only thing this does is to create a confrontational negotiation from the get-go.
Money can do strange things.
A company's choice for a job asked for more money first. When the company said yes, he turned down the job after all. He said he feared the higher salary would create too high an expectation of his performance. People can do some strange things, even when they're trying to impress a prospective employer. For everything you read here, there is someone who swears that it's true.