Snickering does not constitute valid grammatical criticism.

A snicker is the most articulate, learned, spontaneous and succint of all grammatical criticisms, Faldage.

If that makes it 'invalid', it is because it trivializes any other meaning of "valid".

If you stub your toe walking barefoot thru a room in the middle of the night, the pain you feel will be real enuf, even if you can't make a "valid" medical diagnosis of the damage at that very moment.