I only have experience with acrylic paints, but I noticed some extreme variations in different paints I purchased in the past.
Consider anything you can buy at a discounter rubbish and not worth your money. Never buy any paints in anything like a Dollar / Euro store or the like. Also stay away from beginner paint sets.
Recommendations from other painters can help you a lot. But you have to be careful that they are honest recommendations and not just sponsored advertisement. The text reviews on different online platforms can also give you valuable information, but you have to take the time and find out which of them are genuine and which are empty words or paid advertisement.
When you actually go into a craft or artist supply store, you'll most likely notice different paints of the same manufacturer arranged in different categories. Those are usually:
- "College" or "Study" quality: often big tubs of paint. Cheap in comparison to other options but good enough for art students and hobbyists. These often have a liquid consistency (to make them cheap). One example (by Schmienke) costs 10€ for 200 ml.
- "Akademy" or "Studio" quality: slightly smaller tubes with a more viscous consistency and a higher price tag. This is probably the golden ratio between price and quality you should go for. One example (by Schmienke) costs 15€ for 200 ml.
- "Artist" or "Professional" quality. The production of these involve special technologies to make them smoother and combine the pigments with the binder in a special way. They usually have the highest pigment content and the most viscous consistency. Certain specialty pigments (like semi precious stones) are only available in this category. One example (by Schmienke) costs 8€ for only 35 ml, which makes it 45€ for 200 ml.
You don't have to go for "Artist" quality unless it's something you value. You could probably test a few "College" or "Study" grade paints and only upgrade to "Akademy" if you still don't get the desired result.
When online shopping, it's a lot more complicated. Anything cheap or advertised for beginners is probably too liquid. Some online shops offer pictures of the opened tube, which can be a clue to the consistency. Others advertise the high pigment content or the thick, creamy consistency. As mentioned above, text reviews can contain valuable information, for example if someone complains about the liquidy consistency.
In the end, you may have to try different paints until you find you personal favorite and stick with it. Skip the cheap paints and start in the middle price range.