They might not be bad guys, but they make a substantial portion of their money when players move, so it's certainly in their interest to keep their clients active. Then the discussion becomes are they acting in the best interests of their career or their short term finances.
If you were an agent that was going to make £10k from a player extending a contract at Motherwell or £30k from a signing on fee at Exeter City, then a lot of the time it's going to be cream teas all round (jam first, unless you're a serial killer).