[motornut]

Ask for receipts with serial numbers.
And one for shipping too, my friend owns a pro audio shop,his tecs can do some "sub" repairs in house.
You can check a speaker, subs have a big throw,so you can move it gently in and out.
Nothing hard that would leave a mark.
But any crunching binding = not good
Make sure the grill/seat/etc isn't touching.
The speaker baskets can get bent/ bind be sure nothing can hit the rim.
Was he implying "your fault "?
A professional installer should show your son, "it's limits"
If not be sure to ask.