I know it's claimed by many zero-carbers that bacteria aren't needed, but there's certainly no truth to claims by some other zero-carbers that the guts of carnivores/100% meat-eaters are sterile. So, the way I see it, bacteria are needed on an all-raw-meat diet, but not in the same quantities as on a raw plant-diet.
I agree with you about carnivores digestive tracts not being sterile. Meat provides nutrients that will support bacteria as do carbs. The bacteria may be different, but they are there none the less. High Meat is certainly an example, as is the bloated dead cat on the side of the road. I think the major difference is that our bodies are able to digest the meat more fully leaving fewer nutrients for bacteria to live on so I would expect the overall bacteria count to be low. Plant material on the other hand, is full of things that we can't digest at all, thus leaving a large nutrient load for fermentive bacteria (acidopholis anyone?) and yeasts (can you say candida?) that can break that stuff down.
When doing the vegan thing I found that probiotic supplements were helpful, but once I reduced carbs to a minimum (this was even before I went Zero Carb), I found that the probiotic supplements no longer did much. I think they were useful on the high carb diet because they helped overwhelm the less desirable bugs like candida, but once I reduced carbs below a certain point there just wasn't enough fuel to support either the candida or the pro-biotics, both of which depend on carbs.
From my experience, the High Meat effect seems to be related to waste products created by the putrefactive bacteria as they break down the meat, as the energy high seems to be rather immediate after consumption - similar to the quick effects of consuming alcohol which is a waste product of fermentation. It is interesting that the timeframe for the "high" or whatever you want to call it, of the two is similar. If the energizing effect of High Meat was due to the probiotic action upon the nutrients in our digestive tract I would think it would take a much longer time.
Remember it doesn't require much of some chemicals to create an effect. As little as 1/2 milligram of some psychotropic drugs like Haldol can lay you out and make you a drooling spastic with little or no muscle control for hours. Yeast and carbs make alcohol, who knows what those putrefactive bacteria are manufacturing in High Meat?....
Lex