yogurts

First you need to define "bad".
Secondly, you need to understand their purpose and origin. Lets start with acidity. The acid in yogurt is a biproduct of the bacteria which breaks down milk sugars. These bacteria break down lactose and make lactic acid, the same lactic acid you feel in your muscles when they burn during exercise. Your body has a method of removing lactic acid and converting it back to a form of energy. However in yogurt the acid is removed via neutralization. This is as simple as adding a counteracting base that creates water.
Thickners in most food are simple processed soy products or milk products like proteins( whey or casein). They can also be plant derivatives such as fibres.

I would not frett to much about the small products. All neutralizers and thickeners and any other additives have to be approved by the Food regulatory body in your country.
So keep eating that yogurt! Yogurt has bacterial cultures that help the flora of your intestines and aid in digestion. I suggest a fat free greek yogurt, which has little no fat and a generous supply of protein helping you to feel fuller for longer!
But you knew that, didn't you?
kj

*KJ is a municipal fitness appraiser, a rehab personal trainer, a kinesiologist and an advanced human nutrition student.*