OSU, I'm going to have to go ahead and sort of disagree with you on a few of the points you made.
-Check what kind of registration the car had. If it was a Commercial, Rental, or Fleet vehicle, there's a much higher chance that it wasn't taken care of as well as if somebody had bought it. There are probably more dings, stains in the carpet, etc. and probably wasn't maintained as well.
Most commercial, rental, and fleet vehicles get regular maintenance in accordance with the manufacturer'specifications. There's no one in Fleet Operations looking over the shoulder of your average motorist, so when "somebody" buys a car, they may maintain it properly, and they may not. I have seen several vehicles with blown engines because some bone-head motorist never changed the oil. You can make whatever assumptions you like about the way the car was driven - everyone's heard the stories about how badly rental cars are allegedly treated, and you can't really prove or disprove such beliefs, anyway - but I don't think that it is prudent or responsible to assume that fleet vehicles aren't well maintained.
Definitely an irregular pattern of driving, and anytime you put a large amount of miles on a car in a short time it's not great for the car.
I don't know where this information comes from, but it is dead wrong. I'm not sure that establishing "irregular driving patterns" is a useful function of CarFax reports, but I can tell you that there is nothing harmful about accumulating a "large" amount of miles on a car in a short time. Studies by oil companies and auto parts manufacturers have proven time and time again that over 95% of engine wear takes place in the first few seconds of operation, and that the difference in wear between a 5 mile trip and a 500 mile strip cannot be measured even by the most sophisticated engineering techniques. This has been generally accepted for many, many years, hence the preference most folks have for used cars with "highway miles".
If you see one that's been at the dealership for over a couple months, chances are you can get a great deal if you haggle with them.
This is less and less accurate nowadays. Most dealer inventories are floorplanned today at substantial interest rates, so that they cost money every month that they sit on the lot. This cost is calculated monthly and included in the dealer cost for the vehicle. Since dealers rarely lose money on a vehicle, the end result is that the lowest price the dealer will sell the car for actually goes up every month the car sits on the lot. Dealers love to sell a new or used car the same day it rolls in, before they have to pay interest on it, and that is the time to get the absolute best price.
Your mileage may vary.