As this was raised again in the V thread, I thought I'd give my opinions (please remember these are my opinions and not intended to upset anyone - I know some people get a bit tetchy on this subject)
Firstly background -I've been an avid collector all my life across multiple items. From comics, fine wines, whiskys, 1st edition books, animation and original artwork and other stuff !
I have always kept everything sealed. The packaging is part of the product and therefore any tears, rips etc mean that (for me) the item is not in mint condition.
If an item has been opened then the best it can be is excellent. It doesn't matter if there are no defects, because the original seal has been removed then it cannot be mint.
With steelbooks, I know people say that because I haven't opened something then I can't say it's mint, but this is a Schrodinger's cat argument. If the item is sealed and appears to be defect free, then it is mint. If it opened and defect free, then it is in excellent used condition.
If you could call an opened steelbook mint, then an opened IM FS would command the same price as a sealed IMFS with stickers. I have never seen this happen.
Please remember these are my opinions and how I judge something to be mint condition. Others have differing opinions, however they try and enforce them on people.
People should be allowed to collect how they see fit, with no judgement from anyone else.