This would be a good honeypot. Randomly generate a 32-character SSID and send out a probe request with that. To have greater confidence, you could randomly generate another SSID and send out another probe request. If both are accepted with a similar signal and noise level, perhaps it is one of these karma APs. (The process could be fine-tuned, generating N number of random SSIDs and specifying the range for signal noise levels)

You could then war drive to amass a location of suspected karma APs.