what actually works to clean blinds properly?

Depends what they're made of. Wood or faux wood venetians: close them flat, wipe down with a microfibre cloth (an old sock over your hand works just as well), then flip them the other way and do the back. A barely damp cloth with a drop of washing up liquid for greasy kitchen ones, but don't wet real wood much, the slats warp. Aluminium and vinyl ones you can take down and soak in the bath with warm soapy water, then hang them back up to drip dry. Fabric verticals just get the brush attachment on the hoover and spot cleaning.