The answer IMHO really depends upon your collecting goals and resources.
There are many classic commemorative that have been in some way mishandled over the years - damage, graffiti, cleaning, etc.
Many of these have been encapsulated by the various
TPG as 'authentic' with the appropriate qualifier as to why not gradable.
Should you collect them ... that depends upon you.
The positive side is that they maintain their original historical meaning and purpose for (normally) significantly less cost than their certifiable brethren.
The downside is they will likely never gain much in price appreciation ... as well as the collecting 'stigma' some associate with of owning a molested coin.
If it's the only way you can gain a foothold into this tremendous series of numismatic art/history - then I say go for it.
If you can hold off and acquire enough financial resources to purchase problem-free examples ... that is likely a better long term perspective to take.
David