Most “budget” LBD lists are lying to you. They recommend $45 polyester sacks that wrinkle in the car ride over. For a real formal event — wedding, gala, holiday party — that dress needs to hold shape, resist shine, and hit the right length. I ordered 20 dresses under $100 from 8 retailers. Six survived the test. Here’s what I found. What Kills a Budget LBD for Formal Use — and How to Spot It Before You Buy Three things ruin a cheap formal dress: fabric that looks cheap, poor fit around the bust, and visible lining issues. I returned…