I know what you mean ^^
I sometime have fun in the Gimp, and it is the same.
Let's look what it does with this effect. Ooooh nice, and then if I add some of this. Well no, it sucks, ctrl z, maybe try to add this instead. Woot funny trippy, let's go on with this... and that...
And in the end, it had nothing to see with what I had in mind first ^^