wrote:
We've just had a new kitchen installed in our extension. The worktop is
a speckled black laminate (Duropal). After just a few days I'm already
regretting a dark colour - it's impossible to clean as it shows every
smear from every wipe and every crumb.

More worryingly, there appear to be areas where the finish is "dull"
(even though it's not a gloss finish), an effect like I'd expect you'd
get if it were rubbed with wire wool. I have tried good old elbow
grease and a few kitchen cleaners (Mr Muscle, Bar keepers Friend etc)
to no avail. I also tried some EvoStick glue remover, thinking it may
be some kind of residue, but still no joy.

Does anyone have any tips before I either accuse the fitter (who was a
disgrace) of damaging it, or challenge the supplier suggesting it may
have a manufacturing fault?

The supplier is likely to say that it wasn't damaged when it left their
premises, I would be astounded if they said otherwise. I don't know what the
fitter will say but he is unlikely to admit to causing damage. Without any
evidence of who caused the damage you may need to cut your losses and
arrange replacement with a lighter colour that doesn't smear or show crumbs.