With a little effort, one can prevail

Question

What is common between the following words and names?
(Inspired by this except that I actually know the answer to this one)

Defeat
Kleenex?
Guanaco
Nerdiest
Sardar
Ian McKellen
Dingo
Gun
Diablo
Essayed?
Atlanta
Glycose
Get
Earns
Group
Desmid
Terraculture

The answer is self-confirming.
Hint:

Hint:

Tom · Accepted Answer

I think we may successfully

The list is:

Gareth McCaughan · Answer

Well, the [lateral-thinking] tag is there, so

Gahja · Answer

Maybe it is

That would explain why there are question marks, as

3 Answers