And Eru Smiled

[Nilpaurion Felagund]

...the "temptation" was the little bit of "evil" they have in them. (Boromir88)

I don't think temptation in itself is evil. After, the world's only perfect person was tempted himself.

But I see part of what you mean. Galadriel's temptation...

...when at last all that [Galadriel] had desired in her youth came to her hand, the Ring of Power and the dominion of Middle-earth of which she had dreamed...

(UT II 3 - emphasis mine)

...came from her inherent desire to own the Ring and destroy Sauron with it. A good quest, but the dominion of Middle-earth afterwards?

Gandalf's on the other hand came from his desire to do good. [Sorry, no quotes!] So his temptation is not evil. If he succumbed, he would have thought he did good, then it would get evil quickly.

So there. That's it. all other things that I would have said myself had already been said.

Oh, yeah. Evil never wins.