Very true. Some agents are notoriously chaotic (I was rung up by one assistant, saying, 'We've been sorting out Big Agent's office while he's away, and we've come across your submission; I imagine it's too late to ask for the full MS...'
but even the super-organised ones deal with so much stuff, it's not surprising that sometimes it goes astray. It's not always (or even perhaps usually) because they don't give a monkey's.
Emma