In your primary??

I'm curious about everyones feelings about calling violations/fouls in your partner's primary. The thread about the travel call got me thinking about this. From reading these threads it appears that there are several people who feel it is wrong and get downright pi55ed when it happens. Some have even said there is no way they would call something in their partner's primary even if they knew the partner missed it.
Frankly I disagree with this position. I obviously don't advocate ball watching and realize it is imperative to good officiating to maintain off-ball coverage, but one of the general principles outlined in the NFHS Officials Manual states:

Cooperation: Each official must give full cooperation to coworkers and to the assistant officials. Neither official is limited to calling fouls or violations in their own area of the court. Each official should call fouls wherever they occur and be prepared to help the other official at all times.

So what's the general consensus here?