I think that some way of telling how other players in the game have been liked by past groups in the past would be helpful when forming groups to predict how they will be in the future.
A simple button next to each player in your parties name could do it. A + or thumbs up to give them a positive rating, and a - or thumbs down to give them a negative rating.
This could be kept track of and made visible to other players through titles perhaps, or another way that could not be hidden or turned off.
Pros:
- It would encourage people to try to be more helpful and fun to play with
- It would make the game more enjoyable to those players who are honest and good hearted because they would know in advance who other fun and helpful players are, and be able to avoid those who are rude and mean
- Players that end up with a negative rating may be discriminated against and have a hard time finding a group
- Players may not necessarily deserve a negative rating they get (a "noob" for example may get a negative rating from their group just because they are new to the game).