I understand your point, but you can't actually use their data that way.
Even f the ambient temperature in both rooms is the same, the amount of heat generated by their test PC and yours could be quite different. If you have a hotter video card, for instance, or they are running two in SLI, more heat will be dumped into the case. Similarly, if you have more hard drives creating heat than they do in their test box, you'll have more heat in your PC than in their test box.
In the end, the most accurate measurement for them to provide is a temperature delta between the stock cooler and the tested cooler in identical circumstances. Using the same configuration in a room of the same ambient temperature, they can tell you whether a tested cooler was better or worse than the stock cooler and by how much.
Finally, the best way to determine if you need a new cooler is to determine if your CPU is too hot. If so, you need a better cooler. If not .. nope.