Following swishers across the whole hamband on the waterfall display. Simply qso them where they finally land and ask politiely if they're having vfo trouble.....
or simply state what they've done (you might even send them/others a screen shot via email), or tell them exactly about LIDDY operation.
As for the already obvious and previously discussed modes;
I've seen more T-Rash on the waterfall than I ever realized was going on cumulatively, .. all the time.
Another neat thing is distinguishing CW from continuous tuner uppers, AM from SSB, which SB, some operate on the opposite of conventional for a given band, DRM, PSK modes... all at a glance. The overdriven amps really show up too. Now there's a neat qso possibility if anyone wants to go to the trouble.
I guess I could clean up my signals too if I so desired.
