OP- FUCKING NEVER AAAAHHHHHH
I'm kidding. As long as the cheaty foods are coming in addition to a solid nutrition plan and not a part of the nutrition breakdown, don't worry about a little bit here and there. I went on a 3.5 week bulk in the fall and allowed dirty foods because I was busy and it was easy. Put on about 15lbs in that time period, but a shitload of it was water retention due to the garbage in highly-processed foods. A few pounds of that stuck and I crushed a ton of PR's on the last day of the bulking period, so I'm down with it. I don't think that was optimal at all though.
On the topic of cheats/dieting- I agree that extreme caloric restriction with cheats can be effective for a short period of time, but I don't think it's an effective way to go for a long-term fat loss plan. I did it for a whole semester of college, working on about 1000kcals/day 6 days/week and then allowing one cheat day/week.
I lost 30lbs (started at 220 and got to 187ish at my lowest). Yeah, I lost a lot of weight, but it was REALLY FUCKING BAD for my muscles. My strength levels were so low at the end of that. I started following Thibs' training methods and just eating to fuel serious training and I've since gained about 15lbs. I'm also leaner now, and I've stopped giving fux about scale weight.
So yeah, I think extreme caloric restriction can be a good tool on the short term. But in my experience it is not even remotely optimal on the long term. I'd really only give it a try if I had a period of time coming up when I wouldn't be able to train for some reason, or if I had a competition/date with a supermodel coming up. I don't think exteme caloric restriction leaves you looking very good because it cleans out the glycogen stores like a mofo and brings the flatness. The water loss can be sessi, but it really only looks good if you carb up while drinking nothing, which is just mis.
I'm just speaking from experience though- I'm a meathead and not a walking biology book or anything. I'm pretty much of the mindset that you can do whatever you want as long as you don't bitch about how hard it is/enjoy the results you're getting.
EDIT: I meant "30lbs" not "30lbs of fat." Typo, I promise I'm not that guy