Aussie Hotel to Justin Bieber -- We Love Your Crappy Graffiti

Here's something crazy -- the Australian hotel Justin Bieber tagged up this week has ZERO plans to scrub off his crappy artwork from its walls ... in fact, a rep tells TMZ, they're stoked the Biebs left his mark.

We posted the video Wednesday, showing Bieber spray-painting hideous multi-colored monsters onto a wall at the Brisbane hotel where he was staying.

You'd think the hotel would be pissed, but it's not -- the rep for the QT Gold Coast hotel tells us, "It was a coup for the hotel to have Justin want to paint a piece of art in appreciation of his stay."

The rep adds, "This piece of art is now available to be viewed by fans of the artist and we believe that it is a wonderful addition to the colourful Gold Coast arts scene."