It depends...
It depends on what the borrower wants it for. I really see two categories: sport and defense. I have in the past, and I likely will in the future, loan a gun for sport. Say a day at the range that I can't go to, or hunting. And I guess I would only say yes to someone that already owns guns of their own, and are aware of the safety precautions and risks.
I would not, under any circumstances, loan a gun for defense. I know that seems backwards, but let me explain. If they end up using it, who loses a gun? I do - it's evidence now, in the tender, loving arms of the State.
Don't get me wrong, if a friend of mine is genuinely threatened, they can stay at my house, I'll stay with them at theirs, I'll pay for a motel room - whatever. I'd do anything I could to ensure they made it through the night. But if I loan them a gun, and they end up shooting somebody, I'm involved. If I'm with them and it goes down, I know I'll be able to live with the consequences of my own actions.
My two cents. You get what you pay for.