This question by @ChaosMagick got me thinking. Of course, the Tao being what it is (and therefore isn’t) the only real answer would have to be a combined yes and no. Or that there is no answer. In fact as with most things Tao, the answer is a paradox. But for the sake of discussion, and my sanity, I will simply answer no, and attempt to defend that answer herein.
I have two reason for thinking it’s not possible to become trapped in a dark side of Tao. My first is because the very nature of the Tao doesn’t separate light and dark in a way that would make it possible to become trapped in either. My second reason is that if one were to be ‘trapped’ then one wouldn’t be in the Tao at all.
“The Tao is the One. From the One come yin and yang…”
Within Tao, light and dark are as one. Although they distinguish from one another, they do not oppose, but balance. One cannot be trapped within dark, when dark is always balanced by, and becomes, light.
“The Tao moves by returning. In endless cycles…”
If we also consider that Tao is cyclical in nature, and that light replaces dark and dark replaces light, then it’s not possible to become trapped in either. The Tao never stops, it’s never rigid. The Tao continues to flow on a continuous and circular journey. One cannot be trapped if one flows with the Tao.
So, the two polarities of light and dark are balanced and cyclical; they are harmonious with each other. As with everything else, it is the yielding, the going with the flow, that takes one where one wants to be. If one wishes to escape dark, one must only yield to the darkness, and thereby become light.
If you’re trapped, you’re no longer within the Tao
If one is trapped, then one is fighting too hard to escape and has therefore lost the way with Tao. They are ‘outside’ of the Tao. The very nature of the Tao is in not doing, not acting, not being (and thereby being, acting and doing everything).
People become trapped when they do, which is not Tao. Think of someone who can’t swim and is dropped into a deep pool of water. If they fight and struggle they will become trapped in their fear and inability to swim and will almost certainly drown. But if they relax and give themselves to the water, if they just do nothing, then the water will lift them and they will float to the surface.
And so it is, in my opinion, with Tao. If one feels trapped in the dark, then it’s because one is trying too hard to escape, and is no longer within the Tao. If one stops fighting, stops struggling, does nothing, they will find themselves back in the light.

I am a young child. I’m almost alone in my room. I don’t know why I’ve been sent here but they say I’m bad. The curtains are closed but it’s still light outside and the room is filled with a pink glow. The sheets on my bed are purple. I like the purple ones. I have more control when the sheets are purple. The yellow ones don’t work as well. She chose the yellow ones.
I call the light to me, shape it, colour it into beautiful swirls. There’s a gap in the top of the curtains where they haven’t been closed properly. I send one of the little swirls of light energy up to close the gap. It dances playfully before doing as instructed and I laugh at its playfulness.
I’m sure he’s here with me. I can feel him now. I’ve been anticipating his arrival for a long time. I can’t see him and he doesn’t know I’m here, but he will. One day.
Now she’s here too. The one with the wings. The one I can see. I look up at her. She isn’t touched by the pink glow. She is in my room and yet not. I know she’s not in this world. She’s in my world. The other one. The one from before. My colourful lights swirl around her, excited.
“He’s here.” I tell her.
“Not yet, but almost.” She replies warmly. “Be patient little flower.”
“Will he know me?” I ask hopefully.
She looks at me for a while and I stare back at her as she answers. “One day he will.”
“How long?” I ask, my youthfulness failing to hide my impatience.
“Too long for you to imagine, but no time at all.”
I don’t ask any more questions. I know she wants to leave now.
“Will you be back?” I add quickly as she begins to fade.
“I’m never gone little flower” she replied.
http://digital.library.cornell.edu/w/witch/index.html
The Cornell University Library Witchcraft Collection is an online selecton of titles from the Cornell University Library’s extensive collection of materials on Witchcraft. The Witchcraft Collection is a rich source for students and scholars of the history of superstition and witchcraft persecution in Europe. It documents the earliest and the latest manifestations of the belief in witchcraft as well as its geographical boundaries, and elaborates this history with works on canon law, the Inquisition, torture, demonology, trial testimony, and narratives. Most importantly, the collection focuses on witchcraft not as folklore or anthropology, but as theology and as religious heresy.
These titles were originally digitally scanned from microfilm by Primary Source Microfilm and the images were returned to Cornell University. For more information, please visit the About page.