Linda Blair had some hideous hair don'ts in the movies as she grew older, I think it's one of the reasons her career tanked, she never really evolved beyond the horrible 70's hair styles, so she became dated. I'm sure she kept the permed hair for a awhile as i think she thought it made her look more mature, but it was just wrong. Besides all of those mistakes though,I still have a soft spot for her.
I love Linda, wild hair and all. It was a funky look, but she pulled it off. She had one of the greatest grins ever.