Does the church down the street need a warning sign?
Seriously, if you have been involved in churches long enough you likely have heard of some churches that should definitely come with a warning. The warning I would use for some of these churches is, "Danger, prolonged exposure to this church can be damaging to your emotional and spiritual health".
Unfortunately, all too often, there is ample evidence of abuse, neglect and usually an overdose of doctrine. In almost all of these cases, it's completely avoidable. Too many people love the doctrine, drama and emotion and are all too happy to interject their personal agenda into what is actually a very simple formula. The church is the Body of Christ and we are to reach out with the love of Jesus and care for people as Christ would in love. The scriptures tell us that love is to be forgiving, patient and kind, it's not to be rude or selfish or self-serving.
However, it's likely that because this formula is so simple and there are so few instructions in the Bible on how to "do" church that people interject more rules and regulations. These are likely man-made, not profitable at all and some are just stupid and abusive. Rules and regulations do not make people more spiritual, and conformance to a narrow walk doesn't mean that one is on the correct path.
While some traditions are fine, many traditions preempt that which is actually spiritually beneficial. The Apostle Paul fought against the rigid regulations that easily crept into the 1st century church. He wrote to the early church, "Be careful that no one takes you captive through philosophy and empty deceit based on human tradition, based on the elemental forces of the world, and not based on Christ" (Col 2:8)
Churches shouldn't need warning signs. Churches should just have welcome signs.