Testimony's based on experience with police

Now there are obviously a lot of blog posts about reliability of testimony's but Id like to bring up the point that peoples past experiences with police are on of the main reasons unreliable testimony come up. For example, I remember a witness that was an old lady, and when asked her opinion on the police, she said that she once called them on a abuse case and when the police showed up they arrested the son even though it was another person who was the abuser. When she tried telling the police it was the wrong person they threw her in jail over a traffic ticket violation that was never there. When she gave her eyewitness testimony of mike brown, she talked about how mike brown had his hands up the entire time, and how Wilson fired shot after shot into him with his hands up. She also claimed she walked over and fired more shots into his lifeless body. Regardless of whether this happened or not, I believe her previous experience with the police helped shape her story and may have influenced some details. And looking at the other side, I remember a person who trusted the police and her eyewitness testimony said that mike brown turned around, fist clenched, not in the air, and charged Wilson like a football player. If this person has had a positive experience they are much more likely to believe that the police are not responsible and have their perception changed to mike being the attacker and the officer just doing his job. Police past experiences have a huge effect on this case in my opinion and help shape unreliable testimony.