Something that Annette and Chloe notice with many of our autistic friends and group/workshop attendees are harmful stims, such as skin picking and scratching (and this is called dermatillomania), which can lead to bleeding and scarring.
There are a number of reasons why many of us autistics have these stim behaviours. It may link to perfectionism (a need to remove spots etc., for instance), automatic responses when anxious, or something Annette and Chloe have noticed a connection between: being made to stop “odd” behaviours as children/adolescents etc., and the only thing you can have control over (and can be seen as “normal”) – your own body. This latter point is linked to autistic masking: autistic “acting” so as to appear “normal” and avoid social/family disapproval in order to fit in.
These stims feel good: they may help when feeling anxious etc. But sometimes we know that you may not like that you do these stims. We hope that we can help you understand why you do them, and also help replace them with non-harmful stims instead (e.g. during the stim session three, and by keeping your sense diary).
See the video below on dermatillomania by Cherry Blossom Tree – My Autism Experience 
So, You're Autistic (think you are)? 