Hi Ken,
I don't know if you have used ADSGexchange.com, in which they use thumbnails from this and three other sites via the API facility, to illustrate aircraft on their Global Radar view. The thumbnails link back to this site. It appears that the thumbnail provided is the first for a registration, if there are other airframes which have used this registration, the current one is not shown. It does not identify aircraft type.
Case in point. Aircraft VH- EVQ
This is currently an Aeroprakt A22LS which is not in the database. However the API returns a previously registered Evektor Sportstar. ADSBexchanges database identifies it as the A22LS but this is not detected by the API.
I also believe they have been trying, including private messages, to contact you regarding enquiry limit. I use the site regularly to check aircraft arriving and departing Melbourne Airport, and got a lot of "No image in database", when I know that there is one, including my own.
Peter.