they get red when you are feeling hot because blood rushes through them but the elbow is just skin without any nerves and blood stuff so it would not get red because of temperature
this morning when I was showering I've felt someone patting me on the shoulder but when I've turned around there was no one there. I thought I was just sleepy and ignored it. But now I'm 100% sure I've heard doors to my apartment opening and when I went to check it there was no one there.