If you live in Japan then it is piss easy but in the west it's another story. Even in other Asian countries such as Korea and China it's probably worse than western countries. Yakumo
Just before christmas there was a sealed copy of charge n blast for the dreamcast on ebay and the seller was honest and said he could clearly hear the disc rattling around inside the case. It was cheap anyway so I bought it, the seller nearly had a heart attack when I asked him to unseal it and place it back in the disc holder before sending. In the end though I got a mint copy of the game for half the price of the manual and disc only copy. I would say I am often reluctant to open sealed copies if I get them, sometimes I will treat them roughly in the hopes that the seal is damaged and I have an excuse to open it haha.
The worst part must've been unsealing it and realizing there was indeed a copy of Charge 'N Blast inside
Sealed games are nice because they're in their purest form, if the game means something to you it's nice to have it sealed just for your own personal enjoyment. I was going to buy a sealed copy of Biohazard: Directors Cut which Inflames was selling on eBay but I didn't have the money in the end. Directors Cut contains the Biohazard 2: Trial Edition which is a disc I love quite dearly, not only because it contains a large chunk of the 1.5 artwork, but because it represents a critical turning point in Biohazard 2's development, not only from BH1.5 to BH2, but also from early stages of BH2 its self. Because of that I was quite willing to spend the money so I had something nice to put on display, something that I could actually look at and smile at, knowing what it is and what it represents to me. But that's the only reason I would ever buy something sealed, it costs too much money to build a full collection and in the end you'd never know if they were rotten inside or not. I've seen things like a sealed copy of Goldeneye go on eBay for $800, $800! If you're a millionaire then by all means go for it, but minty fresh is good enough for me, being able to enjoy the quality of a product without risking accidentally breaking the seal is just as good. I do have a sealed copy of Skyward Sword box set though, we'll see what they goes for in a few years time, more than £55 I suspect.