You don't need to be a rocket scientist to see instant oxidization and contamination in a weld. But what do I know ;)
The floor pan welds will fail in corner fillets. The orange discoloration is due to improper shielding.
.... if you say so.
If you run any X bracing up front with out running nascar bars you should have your eyes opened - that X brace there is going to shatter his pelvis on side impact. I would not drive that car on a race track let alone the street. But wtf do I know I only hang around 10 second bmws