The easy answer would be that you ate some soap. I am going to take it upon myself to think that you did not do that. It could be medicine that you are taking. It really could be that you are not rinsing your dishes off well enough as well.
Unless it's something obvious like your mom washed your mouth out with soap, it might be the herb cilantro which causes many people to complain of a soap taste.
you have an unbalance in the vitamin and mineral level in your body. Low iron tends to come with a metallic taste in the mouth. Its likened to sucking on pennies
The simple answer would be that you inadvertantly ingested soap during your shower or other washing activities. Smell is a large part of taste so if you smell something similar to soap you may be tasting the smell
