Besides the potential legal ramifications (like, you don't already own the actual physical copy of the game), my biggest fear in going to these ROM/ISO sites, is that you will end up on a virus-ridden webpage, so how can you tell if a site like this is too risky to use?
Completely fair, I have the same concerns. I don't know if it helps but I use an incognito browser option to ensure it's a new browser window with its own memory that I close out after I visit the site. I also have antivirus software running as well. That's no guarantee but so far I've had no issues.