I got my tongue stuck to the ice in the freezer compartment of a fridge once (stupid student prank). I had to rip my tongue off and left some of it in the ice... not a good effect.
Okay. I froze a portion of pork. Defrosted it, as you do!, and although the meat was lovely the crackling just wasn't the same. I wondered if it's because it was frozen?
No I don't think it makes a difference if the meat starts off good quality. I buy my pork and other roasting joints two or three at a time because the decent butcher is quite a drive away. I always freeze all of the meat but one piece which I cook immediately and have noticed no difference in the crackling or anything else. Mind you the meat is free range, un messed about with and jolly expensive but you get little shrinkage and excellent quality
I find frozen tuna acceptable but not as good as fresh never frozen. You can eat the fresh never frozen a bit rare but the frozen needs to be cooked through to taste okay.
I think the problem with frozen pork and poor crackling is due to the skin not being left to dry out. If the skin is at all moist it doesn't crisp up as well.