That would certainly be one way to find rogue access points. However, you will only find them if they are sending packets. If they are just acting as a bridge, you will only see the MAC address of the wireless card on the PC as the source, not the MAC address of the WAP. Also you would have to be in the same broadcast domain as the access point to capture any broadcast packets it might be sending out.
I guess you could look at the ARP cache on your routers and try to find those Organizationly Unique Identifiers that matched the WAP addresses..
A method I have found very useful for finding rogue access points is to use NetStumbler, or its little brother Mini-Stumbler. These are both products that will send out wireless packets looking for WAPs. If the WAP is set up to broadcast its SSID, it will respond to NetStumbler.
The product allows for a connection to a GPS, so you can pinpoint access points. We have gone as far as to import the summary file into MS Streets and Trips and produce a map showing all access points.
Mini-Stumbler will run on a Pocket PC, which makes it very nice for handheld access point discovery. Fortunately both products are free. Just check the website to make sure your wireless card is one of the supported ones.
mpennac