I see an EMDR therapist for trauma therapy and we use different grounding and self-calming techniques so that I will be able to re-ground myself once we get into memory processing. There are different "protocols" for this, some of them I like and some of them I don't. Honestly, most of them require visualization and imagery of some sort. One of the ones I am still learning to use relates to color. I am asked to focus on any uncomfortable physical sensation in my body and consider it in terms of color, texture, size etc. Then I am asked to imagine a healing light (of the color I most associate with healing) flowing down into my body and enveloping the physical sensation.
Honestly, I am really not into this kind of stuff at all, but I am giving it a go because T wants me to try it.
So earlier today I was very triggered and dissociated but I have some work I need to do, so I used some of the protocols she has taught me to try to ground myself. I tried 3 and it was the last one - the color one - that worked for me on this occasion. I don't "like" them and I think they are weird, but I am glad to not be triggered anymore. I was glad for my mind to calm down and be under my "own control" again.

There are lots of different mind tricks to use when your mind is under stress to help get calm again - that is all these things are. All they are really doing is getting your mind concentrated on something else other than the things that are disturbing you in the moment (for me, dissociating and triggers, for you - cockroaches maybe?). I don't know how open you are to trying different techniques tht don't involve visualization, but there are simple ones about observing your environment, focusing on rate and type of breathing, stuff like that. They are basically just self-calming techniques. Some people like to visualize, thus the focus on colors etc.

I personally don't see them as "bad therapy" at all. It's just stuff to help regulate your nervous system.