I reiterate...you ask excellent questions and I thank you so much for participating in these topics, Dawn.

Red is prevalent in spirit photos. Like the
photos of my son upon birth and my toddler niece. The red
spirit of a young woman who showed up for her graduation. Or in the photo of the spoon-bender man in the midst of psychokinesis.
But as to what red means, I have often wondered because I so love the colour red. I am sure there are many interpretations. Interestingly I have lately received several spirit lessons on colour. These lessons occur during the night for me when an advanced spirit teaches me truths about reality and I am able to ask questions (very cool stuff).
For me, I have learned that red is spiritually representative of the physical path of life, whereas blue is representative of the purely spiritual path. But I best start a new topic on this for further explanation.

Meanwhile, perhaps a soul/spirit whether on its own or surrounding the body, shows up as red on the physical plane such as in photos.