@Edent I think the idea is cute, but some human factors might make it a bit risky for some users and (services?):
• A user may wish to ensure a particular service account cannot be tied to their main online identity. If they sign up to Twitter as @MyUsername and also as @anonymousconfessions with two different email addresses at the same domain, they may be deanonymized if the same unique (or otherwise matchable) image is set on both accounts.