My sister had serious interest issues in high school and didnt finish college (didnt feel like it). She tested well on standardized tests before college, partly because she can "figure out" what they are asking for (i.e. if the answers given are 2x+5; 2x+6; 3x+6 and 4x+6 the correct answer is usually 2x+6 )
She has since gone on to kicking butt at her jobs and being a top performer, she just had to care. She doesn't show as a normal dorky "smart" person but she obviously is smarter than the average bear.
I really think (some) can do really well at what they are interested in.
My mom is obviously intelligent and is esfp, actually.