When an evolutionist testified in the famous 1925 Tennessee Scopes Trial that are "no less than 180 vestigal structures" in the human body, was he correct?
Uh, No. (Duh!)
We do know, however, that the human appendix doesn't hold and decompose pounds and pounds of course and difficult to digest vegetable matter. That much is wildly obvious just from the fact that it's far too small. Whatever secondary functions it may retain, or whatever new functions it may have acquired, it is undeniably "vestigial" with respect to the primary function it "used" to have (does have in most other animals -- i.e. the "normal" function of appendixes qua appendixes) of digesting mass quantities of food stuffs that would go undigested if not held for an additional period of time in the digestive tract.
It's probably an underestimate if you include every possible case. But it's meaningless in itself to simply say that a structure is "vestigial [full stop]". It can only be vestigial with respect to some phylogenetically former state AND with respect to some specific function. Since most structures have multiple functions, a particular structure or organ might well be vestigial with respect to some function(s) and at the same time advanced with respect to others.