You could take the amount of posts a person has made on Bitsharestalk and use that as criteria for earning a badge.
That's some eagle-eyed criteria. Might need an additional factor or two.
Exaclty. Luckybit is right, that particular example is objective and easy to establish as a basis, just like the "newbie", jr member", ... "hero" designations of this forum. the SMF allows admins to set the number of posts for each objective label. This is precisely the type of criteria I am in favor of. The "rules" for such assignments can't be anymore objective than numbers.
However, as donkeypong says, that's only one factor, and it may not be that important compared with others. My point is the more factors you can gleen universally and objectively from transaction stats, like the number of transactions, the easier it will be for everyone to make normalized judgements.
The aggregation of the factors into a single label, badge or color becomes a problem for how individuals utilize the label in their decisions. The aggregation into a single badge or label might be very useful for some and be terrible for others, depending on how each factor is weighted.
As a compromise, I could see the value of a badge or label as long as the criteria used to determine it is clearly defined. It would be useful first to take a poll of what factors people here use to evaluate transactions and trust levels.
If each of those factors can be measured by the code and surfaced as a number, individuals can apply whatever weighting they want to each to come up with their own label or badge.
For example, and these are purely for the sake of making my point:
number of forum posts (0 - 100 = 1, 100 - 500 = 2, 500 - 1000 - 3, .......)
amount of time online (% of 24 hr day)
amount of time away (% of 24 hr day)
how many tips held (< 50 = 0, 50 - 100 = 1, 200 - 500 = 2...)
how many successful transactions
avg amount ($ value) of transactions
most traded asset (BTSX = 10, BTC = 5, BitUSD = 4, BitGLD = 3 etc...)
Sum all of the weighted criteria above to come up with a number, that number determines the badge image/color/text.
The weighting (to right in parenthesis) could even be set by preferences in the account. Which factors are used may need to be limited, or not I don't know. Which factors are available in the client vs. on some "account rating" website I don't know.
I believe if badges can be issued based on criteria that can be influenced by an organized group of account holders it will lead to problems. In the example above the "badge" is very subjective based on the weighting criteria each user defines, but the data that supports that is highly objective, obtained from the blockchain or other public info.
I could imagine some sort of "universal weighting profile" that gave each factor equal influence over the final number, and that weighting critera could be considered a normalized reputation value. But individuals could set their own personalized weighting and their badge could be different. A public and private badge if you will.