I just bought an R65 which had only done 150 miles since its last test. I checked all the usual stuff but missed a rumbling wheel bearing on the front wheel ( there was no play at all strangely enough!). When I stripped the bearings out I found that they had pitted quite a bit. Just goes to show, you can't take low miles between tests as showing the bike to be A1! I am now checking the grease and bearings on the rear as a precaution!

do they check wheel bearings on a test?

probably do, but you are right, you cant trust that the MOTer was thorough!

of course the check them but wheel bearings can rot away for numerous reasons, moreso from trapped water when puttin the bike away wet.

I usually strip and grease bearings every couple of years as I don't do a lot of miles and rarely go out in the wet! Wheel bearings are checked for play and noise on all vehicles for MOT (they are not stripped but you can feel the excessive play at the wheel or hear the rumbling noise). Excessive play shows a worn bearing. Noise (rumbling) shows that the bearing surfaces are either pitted with rust, or worn away. The surface of the bearing can flake away if greasing is forgotten or the grease/lubricant becomes contaminated. Grease can dteriorate if the bike/vehicle is stood for a long time without being used.

A low mileage bike can also mean perished tires and low tire pressure , out of date brake/clutch fluid, stiff cables, dry suspension joints...

Absolutely! I heard about someone with an old MGB who bought "new" tyres which burst at speed on the road. They were over ten years out of date. Caravans blow tyres regularly after long winter layups. I often see caravans on their sides after blowing tyres on the A47 towards Norfolk! Good treads but cracks in sidewalls. Caravanners beware!

Not just caravans..

A mate has a 79' DT125 that still has the original Yok's on it

Wheel bearings can always be a problem and suffer most from over enthuesiastic cleaning, jet washers are notorious for causing wheel bearing failure as they force water and cleaning fluids into the ball races on the bearings, I have seen bikes that have been m.o.t'ed and only ridden for a couple of hundred miles after with destroyed bearings, once corrosion starts to set in the bearing can be destroyed very quickly.

Not a problem with me then, my bike's for genuine, authentic, original dirt from 2004

UPDATE :-
I checked the tyres after a trip out and found the front to be cracking in the tread. I replaced the tyres and found that they were also cracked right around the edge where the tyre meets the rim, just under the rim (which could not be seen with the tyre on the rim). Be warned! They appeared fine when I checked them last week - I checked them myself and the bike has recently been MOT'ed. The cracks just appeared after a rideout locally. Mike

That sounds real strange MrT,...post up some pic's if you have them, im interested to see what this looks like. if its a manufacturing fault then probably best to inform the tyre makers.

It's just age. The tyre was hardly worn but old. They harden with age and that's when the cracking starts.

i guess if they had not not been used for some time then they could have had small cracks not easy to see and the extra use in your ride out probably just finished them off - lucky you checked them again!