Sometimes when I see an example sentence in a linguistics textbook which is supposed to be incorrect or unparseable, I get annoyed because the sentence seems just fine to me. Garden paths aren't the same to me anymore, either, because after studying them I can parse new ones without much problem. For example, most linguists know the famous 'the horse ran past the barn fell'; because of that, 'the boat floated sank' and 'the car turned went straight' are easier to parse. How do linguists maintain a sense of what non-linguists can and can't do? There are always surveys, of course, but a linguist can't just write every sentence on a survey and ask for opinions on every one.
2 more examples. It has been claimed that starting a sentence with multiple 'that' is not possible; but I am just fine with saying
That that she did that was a bad idea was not a good thing to hear.
Perhaps not the best wording, but I would give it a '?', not a '*'. Triple embeddings are fine sometimes, too, if there's an adverb. For example,
The computer the guy your mom saw yesterday bought broke
is fine with me. Am I abnormal, or am I just a linguist?:)