Your relationship with your dog is determined by the daily habits that you've built together. In fact those simple, subtle habits create the foundation that your dog bases all of his decisions off of.
Dog Trainer's can teach your dog commands, manners, and rules to follow but your dog is simply too smart to think that information is universal. Just like you and I, dogs know who to take seriously and who not to. This does not make your dog bad in anyway, afterall they're opportunists much like us.
Whether we'd like to admit it or not, when the guidelines aren't clear we tend to find the loopholes. Many people try to do the right thing due to the fear of what the consequence might be. Dogs react the same way but if there aren't any repercussions they will continue to fight the rules because they have nothing to lose.
Your dog is paying attention to everything that you are and aren't enforcing. These little moments are what will make or break your relationship.
Of course us Trainers can build a new foundation for your dog but you're the only one that can make these changes permanent.