aka Samson vs. the Vampire Women, aka Santo vs. las Mujeres Vampiro, aka Santo Contra las Mujeres Vampiro
How bad is it? It's a typical Mexican wrestling movie with vampires - not great.
Should you see it? Everyone should see one Santo film in their life.
There are hundreds of Mexican wrestling movies. About 50 of them star a guy in a mask and droopy pants called Santo and, of these, 17 have supernatural creatures. I've seen many of these and they're all pretty much the same, but this is the first one Santo did with supernatural overtones, so it's the one that people tend to see (it's also the most easily obtainable); it tends to have a lower rating than most of his films because people who don't like it don't watch the others and fans of his watch all of them.
A group of vampires are planning on abducting a girl and making her their new queen. The local authorities decide to have Santo investigate, after seeing him in a wrestling match (if that sounds unlikely, I'm writing this in Minnesota, where Jesse "The Body" Ventura became governor once). He gets caught by the girls and they're about to unmask him when the purifying rays of the sun burst them into flames. In other words, Santo was a lucky victim, more than a hero. The effects, acting and direction are all adequate; if you accept the plot, it's not a bad film at all.