Non-Standard RT is everywhere. It's the slang and/or speed of the RT that confuses pilots who are not familiar with the local accent or local slang.
Inbound for Atlanta, I heard this exchange between Jacksonville Centre and one of the local airlines -
ATC : XXXX435, can you accept FL330?
A/C : Standby
waited a little . . . .
A/C : Uuuhhhhh, yeah Jack Centre, Cap'n says we can do 3 3 oh for ya.
I don't agree that we have to be perfect in our RT at all times but that is the worst RT I've ever heard. Bypassing ICAO RT for expediency is one thing, trashy slang on a quiet frequency is just unprofessional.