Tired paintwork.

Yellow looks nice to start with, but is a terrible colour for a car - it attracts beetles and flies like nothing else during summer, and fades faster than any other colour! It's almost impossible to get a paint match after a year or so, even if you have some of the original paint left, it looks different. I went for the patchwork quilt look with various shades of yellow touch-up paint, then gave up and left a lot of it in primer for a while before getting the whole thing resprayed in a lovely custom-mixed shade of deep metallic purple. Here it is shortly before the respray, notice the chrome shields have gone from the sidepipes too - the poor thing was definitely in need of some attention!

Blotchy at Thruscross