> I'll have the cheesecake if I really feel like it.
That tells me the writing on the wall, and let me be clear about this, the writing is what needs to be written and what people need to read - you're making the decision to NOT have cheesecake when you only kind of feel like it. It's a game of weighing the pros and cons and learning to be satisfied with what you know you should have instead of turning around one day and loving the healthy food more than the unhealthy.
Just as an aside: > I assert most people will enjoy a baked potato with a bit of butter (~1 cal/gram) about as much as garlic bread (~3 to 4 cal/gram).
You're discounting the calories / gram of butter in your first calculation and including it in the second.