It may be illegal and disrespectful but some of it can be funny in the right place.
My favourites in The Free Trade Pub in Byker, Newcastle where it is encouraged in the toilets...

"Scum also rises"

"Give Germany back to France"

and then the one I saw rubbed onto the back of a very dusty BT van, where usually you get the non-hilarious "clean me"

"Ssshhhh Quiet Please. Show some consideration. Assylum seekers hiding inside"

M.KAHN IS BENT

Jed Dowson bucks kids was on a wall up Manor for ages.

"Micky Fisher ate my socks" on the Rec fence and "Black Rogan stinks of Piss" in my back street are my town favourites.

Is it only me that's acquainted with the BIFF NUMBER 1 MACKEM spray in and out of town? It was on the wall of Ritchie's Field for years.

I love one here in Hull.

Pub Name: The Whittington Cat
Spray underneath: "THE DICK 'N' PUSSY"

Christ.

Bet all of a sudden there is a lot more biffs.

One piece of graffiti made me laugh.

I think it was on the Oxy road church notice board,"this Christmas remember Jesus" and some wag had put "why does he want a Nintendo too".

'Gone Cockle Picking' on a boarded up 'Chinkies' on Morecambe sea front!!!!

I remember 'Gatey lvs Wen' sprayed all around the town centre years ago when i was a kid, i wonder if they ever got married

What's the other one?....something like, MICKY FISHER HAS A DEGREE IN HOME ECONOMICS!!!! on the other side of the 'rec.

I was 'talking' to fritter the other day, he's still as philosophical as ever on life

also after the "Micky Fisher ate my socks," someone painted "nine out of ten left backs prefer socks"

Haha, seriously? What exactly was the article about, Biff's day-to-day dealings on behalf of Sunlun?

And who could forget...