Cleanse question

The problem with cleanses is multi part.

1. They're often very low calorie. While this isn't an issue for a single day when you eat very low calorie for multiple days at a time your body has to start burning lean tissue to make up for the missing calories. There's a limit to the amount of calories from fat your body can use, these cleanses surpass that 90% of the time.
2. They are often low protein. Protein is important to preserve lean mass. Combine low protein with very low calorie and you have a recipe for muscle loss. Muscle loss results in a lower BMR, which results in yo-yo dieting.
3. They're usually low fiber. If they really wanted to cleanse the body it would have to have adequate fiber. Fiber is what helps clean out your intestines. Just drinking a bunch of liquids, or even worse adding a laxative, would actually cause more harm than good in your intestines because you are more likely to cause a bacterial imbalance.

You also mentioned people who are obese and eating a diet of purely processed foods. Simply adding lean proteins, vegetables, and drinking more water is all that it would take to significantly improve the condition of the digestive tract (including liver and kidneys). Switching to a bunch of teas or pills or ACV is forcing the body to work harder to balance our pH. It's not cleaning, it's worried you are being poisoned.

Eating highly nutritious foods like kale, spinach, etc is good for you. Any claims beyond that are just noise. You still aren't cleansing anything by consuming them. Just nourishing yourself well.