What should you be looking for with "good" teams? All "good" SWAT teams are trained, experienced, skilled, confident, knowledgeable, tacticians, disciplined team players, and working as a single unit. But above all, they're the "real deal"—professionals. What they're not is arrogant, undisciplined overconfident, individuals, or show-offs, not on the same page, or with "attitudes."
How can you tell "good" teams from others? One way is to watch for smoothness, fluid motion, no wasted motion, quiet confidence, working as one team. This takes time, training, and experience to develop. A good example was a SWAT TV show I watched recently, where the team rule was new troops weren't allowed to be on entry until they completed a full year on the team.
My own team had a similar rule, plus requiring new entry team members to start at the rear, then work their way toward the front on subsequent entries. Only after numerous entries, and close scrutiny by veteran team members were they OK'd to be on point, first through the door. However, this was only valid for warrant service entries, with hostage/barricade entries reserved only for the most experienced troops.
My guess is every "good" SWAT team has a similar rule, because experience is so highly valued. It's called "paying dues," developing trust, teamwork, and tradition that will be passed down to future new troops.
This is little different from the NFL, where most rookies have played football since childhood. Even the most highly touted rookies pay their dues early on, until they're given the opportunity to "play ball".