Anytime I've showered the head of my penis (uncut) becomes adhered to the foreskin so when I pull it back everything sticks and can sometimes hurt. This isn't the case if it's lubricated, moisturized or even used, but it can be a little irritating or even hurt slightly when caught in jeans.
Before you can understand why your foreskin may be sticking to your glans (really a question of mucous membrane to mucous membrane), you need to know a bit about how that area stays moisturized naturally.
There are no secretions per se from the mucous membrane of the glans and inner foreskin. The area stays moisturized and mobile through normal transudation of moisture and contact with other fluids, like urine and semen. Smegma is not a secretion of its own. It's the normal sloughing of cells mixed with transudated moisture and the aforementioned fluids, and most intact guys rarely see more than a "dusting" of it. The normal bacterial flora and moisture of the area is changed with washing, particularly with surfactant detergents like soap. Remember: live, healthy bacteria rarely emit an odor, but decaying bacteria do. So, the goal is to keep clean but to remain moisturized.
It makes no more sense for guys to wash away natural emollients in the mucous membrane area of their sexual organs than it does for women to do it. It makes surfaces sticky and increases the chances of infection. Ditto for your mouth and eyelids... they need to remain minimally lubricated to prevent surfaces from sticking together. Granted, it's hard not to get any soap on your dickhead when showering and skinning back, but there is a difference between washing off all the naturall emollients and just letting the soap run down you. The inner foreskin and glans are ideally rinsed with warm, clear water once or twice a day (more as needed, like after sex) and generally require no added moisturizers.
The suggestions for Aveeno and Dove are good; stay away from antibacterial and other strong soaps in the genital area. Some guys at my gym put a dab of Vaseline on the glans before replacing the foreskin after a shower, but it should be obvious why carbolated petroleum products are not a good idea.