Identify twitter profiles have default image

Yes this is possible!

First find out your list of followers' IDs: https://dev.twitter.com/docs/api/1/get/followers/ids

Then lookup your followers: https://dev.twitter.com/docs/api/1/get/users/lookup

You'll receive "default_profile_image":true for a follower if they have the default profile image.

For example if you query your own Twitter account using JSON: https://api.twitter.com/1/users/lookup.json?screen_name=ajaypatel_aj

You will see:

"default_profile_image":false

Or using XML: https://api.twitter.com/1/users/lookup.xml?screen_name=ajaypatel_aj

You will see:

<default_profile_image>false</default_profile_image>