I've had good luck with free consultations at Sephora, but worse luck at some makeup counters in department stores where the sales people tend (in my experience) to push a more-makeup look. At Sephora I try to find a salesperson who's wearing less makeup because that matches my own style better.
I mostly wear Clinique because of chemical sensitivities, and their colors happen to work very well on me. The Chubby Stick is great - Mega Melon is exactly the MLBB look on me (I love this new acronym, thanks) and there are a lot of different colors. To my surprise, my best (and only) true red lipstick came from a Clinique gift bag, but at least I knew to ask for the pink/cool shade version of the gift bag. All through my teens and 20s I thought my red hair meant I should go for autumn tones in makeup. So wrong, with my skin.
Anyway, I'm just rambling, but between color mismatches and sensitivity to makeup ingredients, I totally hear you on the frustration of buying something that doesn't work. I didn't know until recently that I could return stuff (Sephora is *great* for returns) and it's revolutionized things. Now I go into Sephora, ask for help, try out a full look for the day to see if I'm sensitive, then go back the next day to buy whatever products worked.