Welding Tips and Tricks

I don't know if this has been done or is just a dumb idea but I think it would be cool and/or informational to see some videos that show how to re-do or undo something. Newbies and some of us that don't want to admit it sometimes forget to turn the gas on or don't clean everything good enough or some kind of boo boo's like that and it would be cool to see a video on a few mock up mistakes. I'm sure I've made about every mistake there is but it's interesting to see a new trick to fixing somethings or when good enough might be good enough. We all don't always have perfect conditions with perfectly clean metal or exact bevels so it's just an idea.

It usually just involves a grinder.

I know. I guess I was meaning a non welding test kinda situation. Paint, rust, wind and such.