Currently in a band that was inadvertantly formed from the ashes of a previous band (previous band: Bullet Six, new band: Son of Six) that the guitarist ruined by becoming so utterly paranoid due to his weed habit that it was completely useless but we've managed to form a coherent and suportive outfit that gigs more than we'd ever thought possible.
I suppose it's all down to trust; are you getting the support that you need as a musician from the other members of the band, are they supportive of what you do as a bass player, do they offer constructive criticism where due and do they praise you when you come up with some killer bass riff. are you supportive of your bandmates, do you feel that you're listened to when voicing concerns or asking about structures or chord sequences.
I'm pretty damned lucky with the folks I'm currently playing with as we're friends because of the previous band but at the same time if we didn't have that previous connection I'm pretty sure we'd still have the same rapport. Suppose it's all down to experience but yes, I'm extatic to be playing with these folks