I think Theymos made it very clear that user is responsible for what user is advertising in signature.
Actually user should do investigation that user is not promoting phishing links, scam or fake ICO.
One bounty campaign specially caught my eyes.
"https://bitcointalksearch.org/topic/bounty-impressio-7-500-000-tokens-worth-75m-usd-3350550"
The gain ICO is promising in website that surely looked ponzi (not sure, but remember that they were promising double your money in 45 days).
But still so many people joined this bounty campaign and a legendary member taken the responsibility of its bounty management.
What about the users who participated in this campaign and about the manager?
PS: I think it is time we need to write the guidelines of Bounty campaign management too.
Signature guidelines are already posted in below topic.
https://bitcointalksearch.org/topic/signature-campaign-guidelines-read-this-before-starting-or-joining-a-campaign-1684035