No matter whom you're buying from, it is always best to check the car out for yourself. You're spending $40,000 or more; you need to be sure you're making the right decision. Your definition of "nice" or "clean" may differ someone else's. If you look at the car and decide to buy it, you have only yourself to blame if later you find something you missed. If you buy it sight unseen, you're leaving a lot to chance. And that can result in a lot of ill will and misunderstanding if you take delivery and find something you don't like. This is especially pertinent if you're meticulous about every little detail in your car or anal about any little flaw; if you meet that description (and a lot of us Viper owners do), don't buy a used car sight unseen.
There are times when going to look at the car before buying is just impossible; in those circumstances, you want to be dealing with someone who will give you the straight scoop on the car. The dealers you mention are not going to intentionally misrepresent the car.
This topic is particularly timely for me. A friend just purchased a used Viper sight unseen from the other side of the country, and he's not too happy about the car. Giving the seller the benefit of the doubt, I don't think he intentionally misrepresented the car to my friend. But we've discovered some issues of which the seller was unaware, which make the car unacceptable to my friend. (He definitely fits the meticulous owner description above.) My friend did his homework; he looked at lots of pictures, shipping defect sheets, Carfax, etc. Shipping the car back to the seller for a full refund is not a viable option, as the money paid to the shipper for the initial delivery is gone, and someone has to pay for the return shipping. So here we have a deal where both parties dealt in good faith, but the buyer ends up with a car he doesn't want. And all this could have been avoided if my friend had traveled out and looked at the car before buying.
Buying a car out of state is a hassle. You've got to travel to look at the car, and if you don't like it, you're out the travel expense. And now you start over with another car. If you decide to buy the car, you've got to arrange shipping, etc. In my opinion, if you can find a car nearby to buy, it's worth paying $2,000-3,000 more just to eliminate the hassle.