There is no environment more awkward, more unnatural, more uncomfortable for a politician than a party conference other than his or her own. Being seen with the enemy can risk being tainted with suspicion.
Fortunately Charles Clarke does not worry about such problems. Yes, he appeared in Bournemouth for the Liberal Democrats' bash. But everyone knows he's a troublemaker, as seen in his latest comments to Progress magazine.
"Our leadership is weak, uncertain, tactically unsure and lacks vision," he said.
"For Labour itself the stakes are far higher than the personal futures of a few politicians. It is about the future of the party itself."
As a man who has stood up, in front of the entire parliamentary Labour party, and told Gordon Brown to his face what he thinks of him, Clarke's comments come as no surprise.
He will cause huge headaches to the PM in Brighton, and loyalists will be gnashing their teeth as he carefully undermines Brown's leadership.
They will look askance at his recent trip to Bournemouth. They will carp and criticise, as their only response to his outspoken attacks.
Supporters of Clarke might want to point out that, while in Bournemouth, he actually did a very good job of appealing to Britain's third party.
Perhaps anticipating a hung parliament in which the Lib Dems could play a kingmaker role, Clarke actually played an ambassadorial role seeking an alliance of the centre-left against the Tories.
"I would say to my very good friend Nick Clegg - don't focus on Labour seats," he pleaded.
Brown might wish Clarke would keep his mouth shut in Brighton. But in Bournemouth at least he was on Labour's side.