Can sound deadning fall off?

[spl guru 10+ year member]

I thought you already used it. A lot of people don't like fatmat and say it is just peel and seal from Lowes. They say it won't stick if you go verticle after time. Just what quite a few people have said in the general section.
I have 100sqft myself and will be putting it on the floors. Won't be going verticle with it unless I have too. I bought some SS damplifier for the trunk and doors.

Just got er in today! Now im skeptikal on the roof??