With the Salvation Army, you have a weird mix of people. Good, charitable, wonderful people, but adherents to the Army are allowed to receive baptism in other churches and events like river baptisms that happen in the Jordan.
So you have some Salvationists that are Christians, and you have some who aren’t technically Christians but believe in Christian core teachings. I think the latter outweighs the former, in most cases.
Mormons, JW’s, Oneness Pentecostals and other “Oneness-flavoured groups” believe that the entirety of God is Jesus, and that Jesus is God’s true name. So they baptise people “in Jesus name, Amen.” The LDS Church has a particular view of the Godhead, in that the Father, Son, and Holy Spirit are separate and particularly united in a relationship but still three separate divine beings. They also believe in other gods on other planets, and that we can each become gods at certain levels.
Unitarians, of the modern strand, also deny the Trinity. In fact, the Unitarian Universalist Association outright denies the Trinity, saying that “classically, Unitarian Universalist Christians have understood Jesus as a saviour because he was a God-filled human being, not a supernatural being. He was, and still is for many UUs, an exemplar, one who has shown the way of redemptive love, in whose spirit anyone may live generously and abundantly. Among us, Jesus’ very human life and teaching have been understood as products of, and in line with, the great Jewish tradition of prophets and teachers. He neither broke with that tradition nor superseded it.”
One can also find a special breed of Unitarian who is strictly a Unitarian, someone who believes in the “Socinian” form of Unitarianism. Distinct to this form is that they believe Jesus began His life as a human, and that His form did not exist before He was born. There are other Unitarians that deny the meritorious reward of prayer, the atonement, the necessity of the crucifixion, eternal damnation, the need to repent, the need of sacraments other than baptism and (sometimes) communion. Some believe that God and Jesus are the same thing, much like Oneness Pentecostals and so on.
Therefore, their baptisms are invalid due to their tradition of either denying Christ’s divinity; believing His divinity was God’s reward; so on.
If one has ever encountered “Church of Christ, Scientist,” then it is interesting to note that their baptisms are invalid as they do not practise it with water.
Some SDA churches do not baptise Trinitarian. Often, some congregations might baptise only in Jesus’s name.
Refer to this list if you’re ever curious. I found it intriguing.