Dear Ms. Snark,
What do you think about submission services, such as Writer's Relief?
I think they're a waste of time for submitting novels to agents.
They may be useful for getting a list of places to send short fiction. It's hard to track down some of those smaller journals that only pay in copies, and pub credits are a good investment.
Anyone who says they can find the right agent for you for a fee is wrong.
If they couch it as "help you find an agent more efficiently" they're still going to cost you more in money than the postage you'd buy to find out for yourself.
I routinely reject anyone who submits work indirectly. I think it's the mark of someone who thinks there's a secret to getting noticed or published that doesn't involve writing well.