My Expertise Inability Quandary

one night many weeks ago,a friend drop by my workshop,as he sat on that stool he notice it shook a bit.
In a humor manner he said to me"Yus,you repair guitars but you don't repair chairs?"
I laugh and felt stump at the same time..haha
Yes, I have to admit even though its made from the same thing,its not my expertise..haha.