I will try to be brief, but I have personally had two encounters with carfax and it's uselessness. Encounter number one. I bought a preowned car from a dealer and it came with a clean carfax. After a week, I noticed it was in an accident and had if verified at a body shop. Major accident with bent framework parts kinked in the engine bay. Went back to the dealer with my complaint and low and beyond, they now have a carfax with a claim on it. Apparently, a carfax claim is not issued until the check paid out by the insurance company is cashed. Scenario like this. Wreck car. Get repaired with insurance. Pay with own money to get car out of the shop. Sell car. Cash check. No notice to carfax until the check is cashed.
Encounter two. I bought a 2013 Audi A6 with 6000 miles on it a few weeks ago. Clean carfax. Dealer mentioned condition as perfect. Purchased out of state and brought it back. After a few days determined it had repair work done and parts replaced. I had the car returned and my trade in brought back via flatbed from 4 hours away. The car was repaired by the dealer and never reported even though they used the carfax as a purchase incentive.
As you can tell, carfax to me has meant nothing.

And to top it off they've raised the prices to $39.99 for a single report or $54.99 for unlimited.. half the cost of a PPI basically.. forget it!

I think Carfax has created more problems than it has solved, I now wish there was no such thing as Carfax. Yet the general car-buying public holds them as some kind of gold standard.

I dare someone to post a thread about having an open CarFax :)

Carfax is a racket, no doubt, and very unreliable.

Yet, the best part of the business model is this - You are foolish to buy a used car of any significant value without running a Carfax.

The reason being, when you go to sell it, tons of buyers will look at the Carfax. You have to know what's on it.

Whether it is accurate or not is actually irrelevant, since it's not what YOU think or believe, it's what potential buyers think or believe. And, as posted above, the general public views Carfax as the "Gold Standard." So, that perception is the reality in the used car market.

Carfax has done a brilliant job of marketing, and also of "giving away" the product in the early days, to raising the prices to be very, very high today. It's a tremendous business.