This sounds like a whole paragraph on how “talk is cheap” and thus have little value compared to costly signaling that actually demonstrate something.
If one thinks it about in that way, a generalized community symbol doesn’t really do anything and instead what is needed something that ties directly to the user and his abilities and contributions. What would work is a piece of code that provides information on the account used in Lesswrong, other tracking tools and tests that demonstrate rationality. This may result in competition to “karma up” on the site and perhaps some perverse behaviour, but it should be controllable with good moderation.
Some part of me feels like building a customized barcode format which allows for a stylish symbol for the general community that also provides customized information for each user, but that is likely overkill al the moment.
Hard stuff like this happen to me when getting a gym membership (expensive!) and in a number of other cases where the salesperson bring up a set of reasonable claims (but of course highly biased and selected) in a friendly manner to get me into the agreeing frame before pressuring for a sale.
I find it helps to have defined the requirements before talking to any sales person, if not build up reflexive response to sales people and not attempt to update with likely highly incorrect, biased and difficult to process information in time sensitive communications. It also makes sense to pay more attention in non-routine purchases since the sales tactics is not inoculated against and make take more thought.