Power supply reading high?

I dont think this post belong here but we can all relate with power supplies for all systems.. 

Anyway, I have a 10V Dc power supply for a super Nintendo that reads 15V! is this bad?

Also ive noticed when i opened a few other power supplies like atari's and these dont have regulation! so they can read wierd numbers..

I bought a few new ones and there not heavy at all i thought this odd so i opened one up and found that they are regulated and there isnt a big stepdown prosses ( the heavy part ) 

Anyway im just woundering if 15V is high for a 10v Adaptor?

The 9v adapters stay around 8-10 

Thanks