One way to quickly(ish) check if some one is using your account for a bounty campaign (at least on the same bounty as you anyway, it's a lot tougher if they are using your details in a bounty you are not even enrolled in!) is to go to the bounty spreadsheet and click on the column heading with your bitcointalk name in (I have just used a random bounty to use to illustrate).
As you can see, I have highlighted column B with the username, but can highlight whichever column has your details e.g. Facebook name, Telegram name etc.
Then click on data at the top of the spreadsheet and select 'sort by column B'.
This will then arrange that column in alphabetical order, keeping the rest of the columns linked to the correct participant's name. Makes it easy for you to spot if someone is using your details (especially in campaigns with a large number of participants), as their details will now be either directly above (or below) yours. All you need to do now is scroll down to where your name is on the spreadsheet and check for any doppelgangers.
I would like to think that most bounty campaign managers do this to check for any imposters, but always good to check yourself and you can then inform them if necessary. I had it happen to me last week and messaged the campaign manager directly. They sorted it straight away for me. Frustrating, but that's the world we're living in right