Everyone is different on their transition to eating healthy.
Bad food is OK in moderation and gradually transitioning to something better is more likely to lead to long-term success for most.
I had a doctor tell me... 6 days a week eat healthy, just like you guys are saying. On the 7th day, take a break and eat whatever the hell you want. Eat heatlhy or don't on that day. He said, one day a week won't ruin your diet and it will always give you something to look forward to if always eating healthy is a chore. He said, eventually, you'll forgo that 7th days of bad food as you get used to not having it 85% of the time.
A lot of people turn to healthy diets and go cold turkey on the "bad-food". Most fall off the "eating healthy wagon" because they start to dabble in the bad food a little and it gradually become their standard routine again.
Plan for 1 day a week to eat bad and stick to that. If you plan for it, you're more likely to be successful and ween yourself off the bad stuff.