I know there is a lot of talk about wine needing to be stored at 55*, proper humidity, etc. Even at the wine store, when I was going through some older bottles I had, the very helpful owner was pointing out which ones I really needed to drink soon, because they were nearing, or beyond the end of their drinking window. He said a small wine fridge would extend that drinking window.

Ok, so all of that makes sense. However, how is it then ok for wine stores to keep their wines at room temp on racks in their stores? I was in a wine store the other day and saw several French wines that were either late '90s or 2000 vintage stored on the racks in the center of the store.

What's the deal? Are wines like this subject to problems, as they might have been stored for years at room temp? I guess there is no way to really know whether they were stored climate controlled for 5-7 years, then put on the shelf to sell, or if they were on the shelf for 5-7 years.

Do you guys just not buy older wines in non-cellared racks, or is it much ado about nothing, and the wines are typically fine, as long as they are still well within their drinking window?

Storage for a few months at room temperature should not make much of a difference in the ultimate drinking window. Storage at high temperatures, in the sunlight, or upright near ceiling lighting can ruin a wine right in the store.
The owner of any good wine store should know how long the store has had the wine, and how long it has been on the shelf. Furthermore, someone on the staff has presumably tasted a sample of the wine.
Good wine stores also know their distributors, have visited the warehouse, and know their shipping habits.
There have been several threads recently about purchasing older wine from stores that just stack it until it sold, no matter how many years later. Results have been mixed.

Iv'e bought wine with dust on the bottle from my local wine shop. Most recently 1997 Stags leap cellars SLV. As long as their is no sunlight or humidity I think the wines will be ok. However I think wines age faster at room temperature.