When we're around straightforward people we know exactly what the issues are from the start. They know what they want and they are not afraid to state it:
There is no need to guess and decode their intentions
If they don't want to do something, they will politely explain that it's not for them
If they are frustrated about something we do, they will kindly tell us (instead of pilling up anger and envy inside)
If they worry something might go wrong, they won't pretend that all is well
If they are attracted to someone, they will find ways of making their feelings known.