If my opponent can perform some cool magic tricks while doing his wacky rolling, he can roll any way he wants to. I play this game for entertainment purposes after-all.
So... if I were to roll 100% crits and evades... you'd be fine with because, hey, fun!
If someone cheats - or attempts to cheat in any way, they should be kicked out. They're ruining the fun for everyone else.
Regardless of the rolling method, I doubt anyone could roll 100% crits and evades. Also, unless you happen to be playing in a casino in Vegas, I doubt you'd be able to prove that someone was cheating with their rolling anyway.
I think the amount of people who do have mysterious rolling techniques and CAN roll really well (still not 100% though) are so few in number that statistically I would never run into one. And even if I did, I would just chalk it up to them having an incredibly lucky game. So, chances are...it would never happen. But if it did, they better do some **** good magic tricks.