Kayak Storage - is it really not recommended to store right side up?

So it's always recommended that Kayaks should be stored either upside down, on it's side or standing up. Can someone explain to me why it's so dangerous to store a kayak right side up? What if I was hanging it in the garage - do I still need to hang it upside down? Every time I go into a store that sales kayaks, I see many being displayed right side up and who know knows how long they've been in that position. Any light shed on this is much appreciated.

So it's always recommended that Kayaks should be stored either upside down, on it's side or standing up. Can someone explain to me why it's so dangerous to store a kayak right side up?

it's not "dangerous", but it can cause hull deformation if it stays on its hull without proper support.

What if I was hanging it in the garage - do I still need to hang it upside down?

yes, even more so as the pressure of your straps will be on a smaller portion of the hull.

Every time I go into a store that sales kayaks, I see many being displayed right side up and who know knows how long they've been in that position. Any light shed on this is much appreciated.

the ones in the stores are probably on cradles.  cradles can help prevent hull deformation but is no guarantee.  also, the older your kayak gets, the more sun exposure and weather exposure it receives, which can also make the plastic weaker.   its always best to store your kayaks upside down or on its side if possible. 

I store my adventure islands on their hulls, but only because I have a specific cradle that relieves spreads the pressure of the hull weight to the amas as well as to the hull.

One thing to note is that because of the way that rotomolded kayaks are made, they tend to be reinforced on the sides and the top. that also makes them less likely to deform if kept in those positions.  always follow your manufacturer recommendation or else you may void your warranty.