Well Clark's skin is strong as steel, but he's not "STEEL SKINNED" hence why he can kiss someone and his lips aren't like two pieces of stone or how he can lick an ice cream cone and not send the scoop flying with the first lick.
I would imagine that his epidermis is just like human skin (even with the influence of the yellow sun). It should feel smooth or soft to the touch. His dense muscles underneath, however, are a totally different story. I'm assuming those muscles (as well as the effect of the yellow sun) give him superhuman strength and invulnerability. I remember seeing Clark get hit by a car in one of the Donner films, and he was unharmed but the car was damaged.
Or when he does partially lose some of his invulnurability his blood doesn't shoot out of him like a shaken soda can. I mean how fast DOES human semen go anyway? Its a squirt, sure some guys might really shoot it but c'mon... even taking into account his super fast system, every breath he takes doesn't suck all the air in the planet in and out with each respiration. So you're telling me that even the fuckin' act of BREATHING is something he has to control? Super-breath is just that, its super its something he CONCIOUSLY has to control. Sure from time to time a sneeze will create a sort of quick burst of air, but its hardly enough to literally blow out the side of a building.
I don't believe Clark could accidentally break things by doing mundane everything stuff or bodily functions (washing the dishes, going to the bathroom). One thing we have to consider is the amount of force he exerts or applies to an object. Even in human terms, one doesn't wash the dishes vigorously
Besides, he's an adult male, having lived on our planet for at least two and a half decades of his life, and he knows how to be careful not to exert too much force unnecessarily. The "super-breath" power works because he puts much effort into it (though it may not look like it because of his Kryptonian physique), just like lifting a five-ton vehicle with his hands. Same principle goes for having sex with Lois; I think the laws of physics apply to him despite his different anatomy and physiology.