How many here have spent years welding as a living or had formal training for it? I have.
Weld penetration has nothing to do with the method of welding and everything to do with the experience of the welder and how he prepares the object to be welded.
Steel will turn colors when high-heat is applied and cooled at various speeds, so the yellow color of some of the joints may be due to heat or because it is brass brazing, only the person holding it in their hand with the experience to tell the difference is going to be qualified to comment on that.
A really skilled welder would be able to take a tig, mig, stick or brazing rod and join those parts together with any method and nobody could tell which equipment was used if a coat of paint was thrown over top. Welding is not a black art that takes a special person, all it takes is a little good instruction, such as a student would get from a competent metal-shop instructor, and anyone is quickly on their way. As with anything if you get no proper training then you can struggle for years and blame everything but yourself and spread misinformation about welding while you are at it.
