My first impulse in writing up Al Adamson's Dracula vs. Frankenstein was going to be something pretentious about dying men acting out the fantasies of children but then I realized that was dumb and also sort of misleading given the way this appears to have been cobbled together from various sources (this sounds unusual unless you're familiar with Adamson's methods, in which case it sounds completely normal).
Full disclosure: Due to factors beyond my control I got a bad case of the jimmy-legs about 20 minutes into this, and it didn't stop until I was well on my way to my car. And yet even in that restless state I was able to appreciate Adamson's unique exploitation stew being displayed here: Bikersploitation, hippiesploitation, carniesploitation, monstersploitation and Lon-Chaney-Jrsploistation are all represented here and boy oh boy is it weird. As I was watching it I was struck by the probably-incorrect notion that Adamson is like the Sergio Leone of trashy movies, elevating the tropes of the form to their Platonic ideals. Those aren't just boobs, those are The Boobs.
Special notice belongs to Mr. Chaney, who gives a completely mute and mostly slobbery performance as J. Carrol Naish killer houseboy. The character is reportedly mute because Chaney's vocal cords were eaten away by cancer, but his undeniable screen presence is completely intact. He's the cuddliest ax-murderer in screen history, as far as I'm concerned.
In case you're wondering: Dracula beats Frankenstein in the titular slugfest, but it's what you might call a Pyrrhic victory.