Wasted $150 on a 'self-leveling' laser that couldn't handle a 2-inch slope in my own driveway last month. | Concrete Finishers - Freelance Forum - The Community for Independent Professionals
Yeah, that's the worst. I mean, @kai_ramirez38 is right about checking the specs for the grade range. I had to set up a fence line on a slope and grabbed a Huepar self-leveling one. It says it handles up to a 4 degree slope, which is more than it sounds like. You just have to make sure it's actually in its leveling range before it locks, or it'll blink at you.
Manual levels are a pain on big jobs though. Had to grade a backyard patio last year. A good rotary laser with a wide leveling range saved me days of work. My old DeWalt handles a five percent grade no problem. You just need to check the specs before you buy, some are built for slopes.
Honestly, that "self-leveling" claim got me too until I had a similar mess. I just use a simple manual level with a tripod now for anything with a real slope. It's slower but it never lies to you.