I'd say ethics aside, it's inherently dangerous to pirate executable files... so there's an argument to just not do it to avoid viruses.

I personally would never pirate an executable file for that reason alone. A lot of games have demos these days thankfully, so that's a way to get a taste and see if it's worth buying. And in my experience, I got bored of several demos and saved money! And some I realized I would probably really enjoy it.

Ethically though? I mean, if they offer a demo and they're an indie studio, I think it's much more ethical to try the demo.