Why don't antiseptic agents kill 100% germs?

Question

I've seen innumerable antiseptic, mouthwash, handwash advertisements that claim to be able to eliminate as much as 99.9% of **all** germs over a surface...but why not the remaining 0.1% (i.e- why can't they eliminate *all* germs)?------------------------------------------------------Clarifications:**What they mean by "germs":**Being a student of Biology, I can tell that the term "germs" is crudely defined. I would prefer to use "pathogens" (less ambiguous), and I suppose the guys that market these products have (roughly) the same idea in mind. Pathogens normally include bacteria (monerans), protozoans, fungi and viruses... so I guess these are the "germs" they're talking about.**What I'm looking for in an answer:**Why is it that these (commercial) products can't eliminate 100% of all pathogens? Is this due to the inability of antiseptics to act on a particular (class of) organisms? If so, what's the problem there? Or is it because, the guys who market stuff like this assume an arbitrary amount (0.1%) of the pathogens present on a surface (say, the human hand) is located in microscopic niches that are inaccessible to the antiseptic solution? (**If** it isn't possible to provide a blanket statement in this regard, use of *Listerine* as an example will suffice)**In other words:**Is an antiseptic's inability to eliminate 100% of all germs due to its "chemistry", or is it due to physical factors?**Also,**Do antiseptics/mouthwashes/handwashes even kill 99.9% of all germs in the first place? Or is it (as I strongly suspect) an example of marketing fraud?

Answer 1

Answer 2

I think it is both "chemistry" and physical location. Possibly occasional resistance to mode of action. Maybe length of exposure could play a role.

However, it's also a marketing tactic because claiming 100% is difficult to substantiate.