The first impression is that at the basis of these web sites lies a very simplistic methodology, being any historical or artistic knowledge carefully avoided. The standard practice seems to be: first taking a book concerning art, better if dealing with art works of the 17th or previous centuries; then looking for any strange detail, above all saucer-like objects of any kind. Thats it. This way, obviously, it is easy both to detect strange elements and to declare them alien or unidentified in respect to the environment or the period in which they appear.
The point is that no one of the authors of these web sites takes into account the symbolic meaning of these strange elements in respect to the art of the period. Worst of all, by considering these elements as the representation of something real or really seen by the artist, they assume that the artist, eg. an Italian artist of the 15th century or an anonymous Byzantine painter, would actually be allowed to insert any non canonical or un-codified element into a religious representation. On the contrary, in past times the commissioners (those who choose the subject and supervised the execution of the art work - in these cases the religious institutions) would have never allowed the author to insert into a work of art anything other than what previously decided, especially in case of religious subjects. In this latter case, in addition, restrictions were even stronger.
At this point one may wonder whether these authors writing about art and UFOs have ever entered a museum or a church. If so, they would be astonished about the infinite amount of strange objects included into paintings, statues and art works of any kind
Next chapters focus on the real subject and meaning of a variety of art works which appear into Italian and other ufology web sites, and are intended as a strong response to those web pages which publish ancient art reproductions without any knowledge of their real subject, meaning and historical value.