When I was at home, I found a box of old books, perhaps to be thrown away. I recognized many of these from my childhood, little paperback novels likely ordered through Scholastic. Most of them look like such crap now, but perhaps this is only because I'm not a little kid anymore. But two books stood out, either because I treasured them when I was younger or because they are relevant to my current interests. One of those books will perhaps be mentioned at a later point in time, the other is Now Entering Weirdsville! The Strangest Stories You've Ever Heard.
I might describe its contents, but you could probably figure it out based on the cover. The cover has a crooked sign with the title, with some creature in the dark peeking over it. Scattered over the cover are various phrases like, "strange occurrences", "tales of the gross & gory", "just the facts!", "far-out people", "unexpected natural oddities", "incredible places", and "all true!"
Now, this book could go two ways. It could either be a collection of weird yet true facts and stories, or it could uncritically advance all sorts of legends with hints that something paranormal is going on. Based on a few quick glances it seems to be a combination of both. To give a taste, there's an article on the Bermuda Triangle, and an article on platypuses.
The very first story is about the Faces of Belmez. It sounds like this one falls into the category of "uncritically told legends", but let's not treat that as a foregone conclusion before we've even read the article.
The article tells of Maria Pereira, a housewife in Belmez, Spain. She found phantom faces on her kitchen floor. She couldn't scrub them off, and the more she tried the sadder the faces became. After it started attracting tourists, scientists tried covering the floor with plastic (to prevent anyone from drawing new faces) and testing for artificial pigments, but with negative results. One professor actually witnessed one of the faces forming and photographed it. They tried excavating the soil underneath, and found ancient human bones. Someone put a sensitive microphone in, and found "moans and tortured mournful voices wailing in unfamiliar languages". Eventually the phenomenon ended.
It sounds like a hoax to me. They certainly had the motivation (attracting tourism). Investigators may not have found any evidence of a hoax, but perhaps the hoaxers were just too clever for them. A really clever hoax is less extraordinary than centuries-old skeletons manifesting themselves as faces on floors, and therefore more likely to be true. It's also possible that the book, Weirdsville, is not telling us everything, only one side.
I am not very good at investigative skepticism, so I'm not sure I could figure what's missing by myself. My best move is to refer to other investigative skeptic sites, like Skeptoid.
Amusingly, Brian Dunning says this is a very cut and dried case, and instead digresses into things like the cultural context and how even quaint myths can cause harm. Unfortunately, most of the details of how the hoax was perpetrated have been left out, presumably to be found in his extensive list of further reading. I decided that I don't actually care enough about the Faces of Belmez to look for these in a library. I suppose it will forever remain a mystery to me the source of the professor's testimony, or how precisely the hoaxer got underneath the plates of plastic. (I would guess that the plastic simply wasn't as secure as the investigators thought.)
As for those pigment tests, Dunning says they came back positive, and that the city recognized it as a clear hoax. That seems like a weird thing for Weirdsville to omit. Is it... is it lying to its readers? My whole childhood was a lie built to keep me entertained!
Another weird thing is that Dunning says the phenomenon ended with Maria's death in 2004. Weirdsville also notes that the phenomenon ended (without specifying a date), but Weirdsville was published in 1992! There's a whole new mystery for us to ponder.