not true mine are dented all along from front to back and fron is twisted (lowering springs and kerbs dont go lol) and got a bit of rusty on it, and i passed mot fine all they did was hit it with a hammer and it was solid all way down so was fine.
where i work same thing we do check sills in same way and fail same, Btw no i didnt get my mot doen from work, got it done from a different garage cos i wanted it done without bein bais