Seven selected color–magnitude diagrams, showing YSO candidates and false positives, as in Fig. 3. The CMDs highlight the brightness differences of the classes and contaminating objects. False positives (fuzz, galaxies) and uncertain sources tend to be fainter. Galaxies, previously identified as YSO candidates (false pos., cyan diamonds) are generally brighter than average galaxies (bluish dots, other identified galaxies). Looking at YSO candidates, flats tend to be overall brighter in the MIR compared to disk candidates.