This is a very interesting question. I'd have to say that my taste is much more diverse than most...or really bad:) I was thinking about how to measure this beyond just evaluating my catalog and what I came up with was the reaction of others to what I play. I have to be very cognizant of what comes up if I am playing music for other people because in most cases I get strange looks or comments. Random is usually not an option. I have to select things I think fit closer between the boundaries of popular composition....lots of my stuff does not even though I do very much enjoy mainstream styles. Over the past few years my taste has really extended to the fringes including experimental, noise, ambient, minimal, techno etc.
Here's an example of recent additions by artist to my catalog:
Vatican Shadows
Prurient
Dirty Three + Low
Perc
Vadislav Delay
Bendon Moeller
Tall Firs
Bonnie Raitt
MayMay
Soultek
Marko Furstnenberg
Clark Terry
Shifted
Horizontal Ground/Frozen Border/Shed
Norah Jones
Welcome Wagon
Mordant Music (seriously, this is wicked! Want to test your tolerance for extremes? Search out his recent release Post-MorteM/ModeM...but turn it up)
Azealia Banks
Spaceghostpurp
Miles Davis
Richmond Fontaine
Usually there is some classical too but none added lately. Those are just from the last few weeks.