You're absolutely right that it's not going to work every time. Even if you speak up and are patient and polite, you'll sometimes run into players who won't tolerate new players or those who just won't listen to advice. In those cases, when you run into someone you don't mesh with or people who are problematic, you should definitely use the ignore list - this will keep the Group Finder from matching you with those individuals. Another thing that I highly recommend is finding a guild that matches your personal playstyle and attitude. This can take some work, but it's definitely worth it in the long run.
IMHO essentially this is true and very good advice....however, as with most things in life it is not so simple.
It can be frustrating to apply these principles (being tolerant, offering advice, communicating that you're new, etc) when the result isn't positive - I know from personal experience! It can be discouraging, but it's worth sticking with it if you help even just one noob who appreciates it