Much depends on one's starting point. Someone with a score in the 800s could be impacted differently than someone with a score in the upper 600s.
It also depends on whether your question is relative to the simple act of multiple applications, with possibly no expectation of approval, or, if you mean applications AND approvals. Theoretically, one could apply for every card in existance, but with no expectations of approvals. Anecdotally, there have been reports here and elsewhere of folks having 80-120 inquiries per credit bureau and still had scores that didn't tank out to the bottom. A strong credit file can survive these numbers of inquries usually better than a weaker credit file.
Unless there is a scoring model that most of us are not familiar with, no one's score would ever go to zero, since that is not the lowest limit for any of the scoring models, whether FICO or something else. They usually start in the 300s and go up from there. It's the upper limit that seems to have more deviation, with 850-900 the common upper limits,
