I just had a go at a Plants|Expert quiz, and one of the questions was a couple of pictures of tent caterpillars, for which the "correct" identification was Prunus padus.
There was no visible plant material.
I reported it, but who knows if anyone is listening!
iSpot is all ears. If 3 people report the problem, it is automatically removed. Each quiz is independently generated, but the same questions will appear in due course and the silly/wrong ones will be removed if you dispute them within the quiz.
Bottom line is: Computers are stupid, but they can learn.
University of Edinburgh and Biodiversity Observatory (OU)