The only time I hired a tax preparer, they got it wrong and the IRS quickly let me know about it. As a result, I prepare my own taxes with the assistance of a tax program. Turbo tax offers a variety of tax software programs to fit many different scenarios. It is pretty hard to make a mistake when preparing your taxes this way. Other than that one time, I've never had my taxes audited.
My ex-bookkeeper and ex-accountant were a hopeless pair of bimbos. I got fined because the accountant forgot to mail in my return. Filled it out, got me to sign it, and then just never mailed it, apparently. The bookkeeper's office looked like a tornado hit it. She was always late, no matter how promptly I brought her my shit, and she once managed to misplace an entire quarter's receipts. Took her 6 months to find them.
I took a 1/2 hour meeting with a different accountant just to learn what their rates were and what they wanted from me. Naturally, I confirmed that the meeting wouldn't cost anything, and then I later received an invoice in the mail for $600 from them saying I'd been there for 3 hours and signed a letter of engagement. Uh...

I hadn't. In the end I let them extort $200 out of me under threat of sending their made up charges to collections, which I'm not very proud of. They didn't have a leg to stand on so I should have reported them to the... accountant's registry, or something... for shady practices, but I was busy and figured it wasn't a battle worth fighting so I just knuckled under.

Wish I could do that one over again. Like Bogart said of Peter Lorre "I don't mind a parasite but I object to a cut-rate one."
So ya, not really a fan of accountants here.