If you, and I mean you Tommy379 went on a plant and bean diet, then yes, you'd have gas and stink. That is because you have in your own words testified to your heavy meat diet, and all that fiber would start cleaning you out, pushing all the rotten corpses and bits thereof that are still stuck in your digestive tract.
I have beans fairly regularly. I had some for lunch (lentils), along with some noodles in a cooked onion/garlic/soy sauce. A few hours later I had a homemade rice milk with some dates. I have not had gas today or stink. Then again, I haven't touched an animal product in nearly 6 months, so my system is cleaner than then.
Regular animal protein consumers, however, DO (yes, I am agreeing with you here) have bacteria in their guts that break down this animal protein to help digest it.
Vegans (those not just starting out, but have been doing it a while) have different bacteria in their guts based on what they eat. For example, I have bacteria in my gut that actually breaks down plant fiber and converts it to short chain fatty acids and even some glucosides. What that means is that I can eat some cabbage and actually get some energy from it because my bacteria will ferment the indigestible fiber and produce some energy, whereas someone fiber deficient and a heavy animal eater will not have much of those bacteria around to do that job.
It is similar to people not digesting wheat or other grain bread properly - poor mineral absorption due to phytates that bind minerals. But people who eat these all the time actually develop bacteria that makes their bodies very good at breaking down phytates and getting to these minerals.
All of this can be summarized in what is called the gut microbiome. We are, what THEY eat:
[video=youtube;oNm5sE9GAFc]https://www.youtube.com/watch?v=oNm5sE9GAFc[/video]
Plenty of studies in that video for people who like studies that aren't industry funded and targeted to an already biased audience.