Rear Light casings
 

Hi I am getting my 06 Mazda 3 Hatch on Friday.

The only thing that looks ugly on it is the mould around inside ridge of the rear light casings on tailgate and main body.

Are these easy to remove as they're gunna need serious clean, or am I best just leaving them alone. other than that they seem ok. looking forward to my first mazda.

It depends on what you're talking about. The lights themselves can be removed from the car without too much effort. If you're referring to taking the clear cover off then that's completely different. They can't be removed without cutting them open.