The actor and his wife Susan have been married for nine years and are currently expecting their second child, not to mention their other baby – a production company they've launched together.
"This is one of the keys to our relationship," Downey Jr., 49, told reporters at the Los Angeles premiere of The Judge. "I am so clean you could eat off of me. I think women appreciate that."
But for Susan Downey, a relationship that transcends the barriers of home and office takes more than a good loofah – it's also about knowing when your partner needs a little "me" time.
"That's key in any relationship," she told PEOPLE while locked in an easy embrace with her husband. "Whether you're working together all of the time or not, you always have to give each other space and kind of read it. "
And long ago, Susan figured out that any time before noon is when the Ironman star is less than himself.
"He's a little bit of a slower start in the morning than I am," she says with a laugh. "So I have to make sure that there's enough coffee in his system before I start throwing questions his way."
For his part, the actor knows that if a day turns sour, there is one surefire remedy for anything that may be ailing his wife.
"She dances," Downey Jr. says. "So when she gets her dance time on the dance floor with the other girls … It isn't Jazzercise, it's real dance! When Mommy is done dancing, the world is a better place."
Only if it were as simple as a healthy dose of showers, dancing and some caffeine, the world truly would be a happier place, but the actor knows from experience that success in any aspect of his life takes a bit more effort.
"There is always that thing of love and respect," Downey Jr. says, pulling Susan in a bit closer as they share a gaze. "It is work, but it's just so nice."
Then, with a combination of laughter and theatrics, he adds, "It's just so nice not to be lonely! Thank you, dear!"