For what it's worth, I absolutely agree. I'm not a freak about eating clean, but what it comes down to is you need x amount of calories a day to grow, and if most of those are crap it isn't going to do nearly as much for building muscle. Eventually it comes down to the cleaner you eat the more good food you eat in my opinion. For the calories in those four scoops of ice cream you could have gotten a hell of a lot of protein, fiber, good fats, and/or low glycemic carbs. You will feel more full and your body will be more happy. Unless you need some serious calories per day, eating cleaner just makes sense from the point of caloric economy. I have to opposite problem as you, i.e. I have a tendency to be a portly motherfucker. Eating smart is the only thing that has helped get lean (which I'm not now), give me energy, grow, and not feel hungry all the time.
And add some hypers!Your back will thank you as those deadlifts and squats go up.
And for a little inspiration, my 5 rep PR on squats went from 225 to 315 in 8 weeks on the program you are on. It friking rules.
Eating clean all the time is hard for, I have to give a big hand to those who make it a lifestyle. Currently I'm bulking up so I make sure have a lot of protein and carbs and yes I eat some useless crap like ice-cream, sodas, desserts etc...
But keeping the diet clean is the best way to go.