When Frank Zappa used a phrase like "cretinous love songs of greasy simplicity" he may have been thinking about records like this. I don't think I've heard this before today but it sounds awfully familiar - at least I could predict every change. And I love it.
I'm presuming these Markeys are not the Mar-Keys of Last Night fame - in fact I'd be willing to bet money on it. The sound is not dissimilar to various New Orleans vocal groups I'm familiar with from a compilation entitled Lost Dreams.
I looked at Unca Marvy's website and found a reference to a song called Eternal Love recorded by the Heralds, but this is a different song. Then there was a page on Marv's site about the Marquees, which mentions there were lots of groups with a similar name ... You know what? In the past I would have happily gone down a series of alleyways and come up with some vaguely interesting discoveries.