What I mean here is, you're in a tussle with Infected, and there are some other non-Infected involved but they're not *your* people. So here, your Solo/Escort-like options get better. You have a decent chance of kiting Infected around until they trigger on someone else, and then just leaving. Or continue that as the bait method and get them while they're turned, with the added benefit that the bait may be putting up a fight too and holding aggro longer.
The key thing to remember in this situation is that all the strategy is the same for *them*, assuming they're just as much a pitiless bastard as you should be by now. So they can leave *you* saddled with a bunch of screechers just the same as the reverse. Plus, they can be indiscriminate in their targeting - if you have one tied up in melee and they have a shotgun or a full/semi-auto, there is one fairly safe move - "Shoot us both, Spock." Pay as much attention to where the non-Infected people are and what they're doing - if not more...sapiens are sneaky.
If the strangers are visibly better-off than you (better fed, better weapons, better gear, obvious skills), you may consider being less pragmatic (in using them tactically) and more opportunistic - by playing it straight and hoping they're willing to let you tag along with them after the fight. Don't be a chatty-Kathy, but do verbally coordinate your tactics in short clear phrases, making it more likely everyone will survive without pulling in more adds. Think of it like a job interview with a "cool" company (or more accurately, a hard quest with a skilled PUG) - don't try to bullshit them, but do try to make a good impression.
If things happen to go down in such a way that you are the only one left standing...what are the ethics of taking their useful stuff? Ethics? Are you shitting me? Look - odds are, their friends/family/whatever (assuming they have any who weren't present) are not going to be able to claim this stuff anyway. The only real consequence might be if you happen to bump into them and they recognize beloved Bill's custom sawed-off, in which case it will be entirely reasonable to assume *you* killed him for it, so err on the side of caution, and don't flash around stuff you've looted from people.