I haven't kept count, but easily more than 10 times were I have been personally involved with counseling or ministering to the person. Many more times if you count when I have been around other ministeries that engaged in casting out demons, but those have been in public settings and not what I personally consider aproppriate situations. It's possible some of those were not completely real or genuine. Kind of like extreme examples of people falling backwards when a minister lays hands on them, because they were supposedly "slain in the spirit". I've seen someone genuinely slain in the spirit and it's not pretty and nice like the people whe gently fall backwards into the arms of the ushers ready to catch them.
Anyways off my rant and back to your question. The manifestations are not always the same. From our experience (my wife and
I do this as a team) and because of the approach we use the person has already gone through some levels of counseling and has been cooperative and willing in the process. The first sign is the attitude of the person changes drastically in a moment, from cooperative and calm, to agitated or down right resistant and combative. Sometimes there is a distinct change in the tone and character of the persons voice and that is when it starts getting weird as the spirit that is oppressing the person can actually start speaking through the person. That's when you know it's game on and it could get serious. Usually it's the spirit saying things like they won't let the person go, or the spirit saying why it has a right to oppress the person.
Sometimes the spirit will try to physically harm the person. For example we were counseling a young man that had serious alcohol and anger issues in our living room in the winter and we had a wood burning fireplace that had a decent fire going at the time. When the spirit manifested the person kept lunging for the fireplace and trying to stick his arms in the fire. I had to physically wrestle the young man to hold him in place while we continued to pray and cast the spirit out. I'm 6'3" 225 lbs and the young man was probably 5'9"-5'10" maybe 165lbs and it took everything I had to hold him down.
The spirit was cast out in the name of Jesus and the young man fell asleep right there. The next morning he woke up and didn't even remember what happened. He knew something was different, as spiritually/emotionally he felt like a big weight was taken off his shoulders. Physically he was exhausted and said his body was sore all over like he had over done lifting weights at the gym. He also had rug burns on his knees and shoulders, that he was aksing how he got. In his case he had never been exposed or even heard about demonic oppression or casting our spirits, so it was probably better that he didn't even remember the situation. Of course we did explain what happened to him. Honestly I still wonder if completely believed us when we told him what really happened that night. All he knows is that he has been a completely different person for the better since.
That is a more extreme example. Sometimes it's simple as the person just choking, or wheezing, sometimes they throw up. Sometime the person will groan or even scream. Others start shaking or just get jittery/uneasy, maybe a sacred expression or look on their face, even excessive sweating or heavy breathing. Really any physical symptom a person might show when going through a traumatic experience. I have even seen someone's eyes roll back in their head a bit. It's never exactly the same. But I've never seen anything that would be considered beyond the realm of physically possible like levitation or the head spinning 360 degrees LOL!
I'm sure a sceptic could come up with some physio/psychological explanation of these manifestations. However after praying in the name of Jesus and casting out the spirit, we have always seen a dramatic turning point in the person's life when it comes to whatever issues the person was dealing with. For example the young men above was delivered from alcohol addiction and his anger issues that night. He has since gone on to become a loving husband and father and volunteer youth assistant at a local church.