Mini Grey highlights the main logical flaw in the princess-testing plan (aside from why one would want such a wimpy and over-sensitive bride in the first place!) -- a "real princess" would presumably be too polite to mention an uncomfortable bed. A lowly gardener, on the other hand... well, no, realistically she probably wouldn't complain to the queen about her mattress, either. Unless there were a few hours of hypnotic suggestion on the part of the loyal pea!