I am sure that you already know this. Bait and switch means that you are lured (compelled) to come to a store for an item - usually a cheap one - and they don't have that item, so they try to sell you a more expensive one. This is done because it is not likely you would have purchased the more expensive, higher quality one to begin with.
I think the reason that ItsOurTimeNow used the analogy is this. The seeker churches that promote a feel good, "friendly" environment are truly baiting and switching if they are preaching the gospel of Christ Jesus, because the gospel is offensive to those who are not saved. The gospel, the power unto salvation is not pleasant - it exposes our sin and our flesh so that we may turn from our own ways and desires and put our trust in God, loving Him above our own self. The first step as we all will acknowledge is that we must see our ugly horrid sin and admit that we are not able to deliver/save ourselves in order to truly repent. And anyone who truly knows that Lord knows that is not pleasant. And that it just isn't a friendly, atmosphere, feel-goody experience. (But the peace that passes all understanding when then we stand in His grace because of His forgivenes is better than any earthly comfort and desire!) So to invite someone in where they think they will have a warm, fuzzy, comfortable experience and then they are confronted with their sinful nature is a bait and switch. The cheap low quality lure to proposing the most highly paid, perfect quality.
On the other hand, if they are not really preaching the gospel, but the watered down, God is good, God love you truncated version of the gospel then it really isn't a bait and switch. But it is much worse.
There is no bait and switch. We are SUPPOSED to be a place where the love of God is shed abroad. (Beloved, let us love one another.)
A church is to practice the love of Christ and to preach the gospel of Christ.
What is bait and switch would be anyplace where they proclaim themselves Christian, and a person arrives who is NOT greeted, who is NOT made to feel welcome, who is NOT introduced to the gospel in every conceivable manner at the church's disposition.
As Marlowe says, there are some pretty "dour" places out there.....grim people, grim relating, grim outlook, grim proclamation, and grim grimmaces.