Either the user is using the same password on multiple sites. Then this would be a real security issue, independent of the fact if some of the sites store the p

Either the user is using the same password on multiple sites. Then this would be a real security issue, independent of the fact if some of the sites store the password in plaintext. Nevertheless, the vast majority of users do - and that's unlikely to change in the near future. It's just too easy. Many users (the majority? I've seen no statistics for this, but everybody I know falls into this group) do, however, keep several passwords, and assign them to sites based on a combination of 1) how likely the site is to compromise the password (sites that email out plaintext score very poorly) and 2) how much the user cares about the security of that particular account. Which suggests the following use case for fourk's hypothetical plugin: user wants to know what password to use, sees that fooneti.cs is one of those sites that stores easily recoverable passwords, and chooses to use one of the disposable ones.