Here are the photos of the three bathrooms I new to fix. Thanks!

In a rental with a horrible bathroom, I bought tons of square mirror tiles (IKEA) and tiled the walls. It gave space and hid the tiles. when time came to leave, a knife and a bit of acetone removed them without a problem...
Nowadays you can by glass panels (like mirror tiles but in different colours) and do the same thing. Add some bath mats, change your toilet seat to a different colour even use strong adhesive hooks to hang some lightweight posters....
Towels, a potted plant and you're almost disguised!

A bold vinyl decal, large enough and graphic enough to take your attention off the fairly muted background pattern.

Great ideas thank you!