We're always told that space is pretty much full of nothing - a vast emptiness with the occasional star or planet hanging in it. So, you probably wouldn't expect it to have any kind of smell at all - and that's where you'd be wrong.
The people who'd know best - i.e. astronauts who've actually been out there - report that it has a strong and memorable aroma, although what that aroma is depends a little on which of them you ask about it. When returning from spacewalks, and removing their spacesuits, all of them say a heavy stench clings to the helmet, suit and gloves, as well as any tools they've used. Don Pettit, an astronaut in 2003, compared it to the smell of a welding torch he'd used in his youth, whereas others have reported something more akin to seared steak. Scientists believe it's probably the result of high energy vibrations coming from nearby ion particles.