I'm going to get needlessly semantic and picky with you and point out that if you are getting A's on papers, then clearly you are capable of doing something right.
I think you have fallen into the trap of believing that just because a majority of people can do something, you ought to be able to do it to. When we think of things like playing a piano, throwing a ball or giving a speech, we understand that some people are more talented and have better training than others.
I think the same thing is true of other tasks as well. It might seem ridiculous to compare playing the piano with making a bed--but I think that is all falls in the category of learned skills. Perhaps you can't follow 'simple' directions. But I am prepared to wager that you can look at an object in its present state, visualized the desired state, and then develop an approach to change the object.
If the desired state for the bed is to be made, then instead of following someone else's directions for making a bed, develop your own method of making the bed.
As for tests of physical dexterity, we would never expect a person with, for example, Parkinson's to be able to hold a board in one spot. Perhaps, in time, you can learn the fine motor control to spray a bottle in one place--perhaps not.
Why should we expect the same of every person? At some point every person comes to the realization that one cannot do everything. Celebrate the A's, think of new ways to put the bed in its desired state, and don't worry about the spray bottle! 
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--James