For example if they're happy not to wash the dishes for a whole week, you'll find that out and can argue about it when living together, but when travelling you might stay in a hotel where others do the dishes, or might stay for short enough period of time that you'll never find this out.
I'd also recommend doing some projects together. Are you there type that likes to wing it, and your partner is the type to careful read the all the directions? You want to find out these sort of temperament issues before getting married.