The program should encourage contact and visits. Excessive restrictions are a red flag--especially if they are rigid (for example, you should always be able to contact him or her in an emergency). A week or two without contact may be OK, but more than that is questionable. You should be able to talk privately with your child. You should never be told not to believe your child. You should be able to visit with little notice, within reason.
There should be someone of at least a master's level working with the kids most of the time; staff should have been subjected to criminal background checks, and the more educated the line staff, the better. Any kind of group should be led by a therapist of at least master's level--less than that (especially no degree required, trained only by the program itself) is a red flag.
They should never be used in addiction treatment or for those without major psychiatric facilities, staff should be trained in specific restraint techniques, every restraint should be written up and analyzed by staff as to whether it was appropriate and how it could possibly have been avoided, and restraint should be used only by staff. Isolation should be extremely time-limited, and the person should be checked on frequently. Ask also about how often restraint is used--it should be very rare; only every six months, not daily, for example.
Ideally, there should be an ombudsman, whose sole job is to investigate patient complaints and solve such problems. At the very least, there should be a written procedure that allows a child to complain to someone at a higher level of authority than the person who makes the usual treatment decisions about him, without fear of retaliation. If you hear something like "the children are always lying and manipulating" in response to a question like this, you want a different provider. Also, ask if there are state hotlines to which the child has access for complaints.
Again, ideally, you want to hear about clear, minimal rules and little emphasis on punishment. Trivial rules like not being permitted to look at a member of the opposite sex or not being able to look out a window are a red flag. If punishment is used, it should be short, reasonable, and not humiliating. It should almost never interfere with education. If there is any kind of "level" system, it should not punish kids for having "one bad day" with "setback" that involves months of restrictions and/or withdrawal of privileges. There should be a complaint procedure if a teen believes she's being punished unfairly, and levels should not be determined solely (or even primarily) by peers. This can simply become a popularity contest and unfairly penalize kids with poor social skills.
You want a program that seeks medical attention immediately, regardless of cost and regardless of the possibility that the child may be "faking." It should err on the side of believing the kid, basically.
You want to hear that empathetic, supportive approaches are more productive and that necessary confrontations are done with kindness and respect (i.e., "When you do X, I feel Y", and not "You're a selfish monster.")
Here, you want to get a sense that the philosophy is to minimize time away from home and that there are clear rules about length of stay.
You want to hear about a very structured day, but one that includes at least some "down" time for reflection. You want to be sure that education is given enough time, if this is a long-term program.
Blanket policies against medication are a red flag--so are policies that don't have staff supervision of medication use (i.e., they have the teens keep and take their own meds, rather than have a nurse, counselor, or physician's assistant distribute them). Except in cases of uncomplicated addiction, teens disturbed enough to require long-term residential treatment typically need at least some medication. Skepticism about over-medication is good--but seeing medication as a "quick fix" which allows teens to avoid needed emotional pain may miss the complexity of their problems and often represents the kind of black-and-white thinking that is not indicative of the best care.