Saw SHARK6 on something black and sporty looking.
MOD3L on a Tesla Model 3
SPATS on a heavily modified Subaru Crosstrek
METZGR - presumably the name Metzger, on a Porsche 911.
TWEZERS
I assume tweezers, wonder if they are the kind of person who plucks eyebrows and such professionally.
KEENER
Might just be someone who’s keen, but might be because of their association with the Keeneland Race Track. They had some kind of distinctive plate, but I couldn’t see it well enough to be sure it was the Keeneland one.
And MOODYI Presumably Moody one, but . . . that was a front KY plate, so it’s a novelty, not their real plate.
Could it be associated with the Moody Bible Institute?
They’re not in Kentucky (Based in Chicago), but it might be someone who went there. They’re a pretty Calvinistic evangelical bunch, which seems likely for Kentucky.
Could be. I just figured it was a person prone to mood swings or PMS.
That’s where my thought went on that one, as well.
OTOH, a license plate on which one self-identifies as “moody” could be an issue if you get pulled over for road rage. 
GDWTHU I was thinking it was one of the Old Ones before I noticed the plate was one of the In God We Trust ones and the church sticker in the rear window.
ESC RMS There are several escape rooms in the area. No indication which one this might have been for.
HIKE AT
This is very likely not an incomplete sentence (hike at where, exactly?). Given where I live it is much more likely to be
Hike [the] A[ppalachian] T[rail]
Also, NATRUL. I guess the closer approximations were already taken.
AUDTOR
I’m betting an auditor who ran out of space
KGREP - perhaps a new variety of grep that I’m unaware of.
Probably a Korean Grep.
On an otherwise unadorned red SUV: BOX1092. No idea, other than that’s the designation for a medium-size USPS priority mailing box.
PATTY S on a black SUV. Patty was a tattooed grey-haired dude… or he was driving his wife’s car that day.
NYC TLC Plate. ( Taxi and Limousine Commission-- an Uber/ Lyft private car )
STP TXTG
Oh, the irony.
FLAXEN1 on some crossover. Yes, I checked out the driver and she did have long, blonde hair.
KLF LLC on an Infinity sedan. I assume that’s a business the driver owns, but there wasn’t anything to indicate what KLF stands for.
A quick look on the internet confirms that there are a LOT of Limited Liability Corporations whose initials are “KLF”. In fact, there are a lot with names like “KLF Billing LLC”, “KLF Merchandise LLC”, etc.
SD FORD - On a Ford F-150. I thought is would be a Super Duty, but that isn’t part of the F-150 line.
XPECTO - The world’s most predictable magician.
Or Harry Potter fan…
GEB ACHT
German for “Pay attention, y’all.”
BBFAN
Probably a University of Kentucky fan. UK is often called Big Blue. And it’s fans ate the Big Blue nation.
(Aldo, I think it was the UK specialty plate).