Two things to remember: The route planner does not always, no matter how you filter it, limit your route to the stars that you prefer. If it can find no other way to get to the place you want to go, it may send you through a couple of non-scoopable stars, IF YOUR SHIP, AT FULL FUEL CAP, CAN DO IT.
2). If the star you exit at after any jump is scoopable, fill up your tank. The route planner assumes that you will. Also, it's plain idiotic not to, as it's free gas and jumping until you're almost dry isn't any faster than scooping along the way. The route planner uses common sense, human beings don't know what the words mean.
Third point: If your galaxy map (check it often along the way after you're plotted your route) shows a dotted line after a mark with a star symbol with a drop in it, it means THIS IS YOUR LAST CHANCE TO FILL UP UNLESS YOU WANT TO CALL THE FUEL RATS. Don't ignore it. It's not a suggestion, it's the law.
Good news is, you don't really have to pay much attention to it if you have the sense that G-d gave geese and refuelled every chance you got along the way, because the plotter's assumption is that you're not an utter twit.