10 years in a trailer reminds me of a Discus 2a I bought
Hadn’t been out for 7
Was mouldy on the outer surfaces which did come up ok after a serious clean, sand and polish
The upholstery was rotten right through and in general the glider was in a terrible state.
I dare say it does come down to the environment it is kept in. Dry and warm beats sitting out in the cold wet and snow