Clearly there are many potential sources of data other than the wigle client on your phone. It's certainly possible that some of this data is leaking from other applications or sources - consider for example US trucking company Sprit which use a WiFi enabled logistics tracking system; a rogue IT person on the backend could probably acquire significant data thru that. Somebody could have reverse-engineered the skyhok XPS tile-cache encryption scheme enabling rogue android flashlight apps all over the world to scrape data... consider Apple with their consolidated.db fiasco of years past - Navizon was willing to pay YOU cash money for that data (see
https://web.archive.org/web/20110604191 ... =13&t=4774 :) ... and let's not forget about the latest craze of warshipping.
Anyway, Wigle architects have a significant task to integrate all these differing forms of data and weed out the junk - my concern here would be obsolete (very old) data, which is certainly better than _no_ data but possibly much worse then fresh data in some cases.
Look at the 'bad data in texas' thread, query the GPS coords for Hwy 290 between Austin and Houston, it looks like somebody just driving back and forth while running "FakeAP"
http://www.wirelessdefence.org/Contents/FakeAPMain.htm
I for one am passionate about "good data", and have pretty much turned wardriving into a "bodily function" with no less than 2 radios operating on my person at any given time, and as many as 9 in my vehicle when driving.