It’s either bare 6061 with polishing rouge embedded into it, or some of the clean anodized shit. The latter of the two is the worse of the two.
Always buy raw material if you’re going to weld, clean and prep. You’ll never get a clean, proper weld on either of the two prepped materials without some serious cleaning and even they it’s a basket case. Rouge is embedded into the material, it burns and creates gas pockets in the puddle. Anodizing is just plain jane surface oxidization and you cannot weld through it.
90% of the time the raw material is cheaper than polished crap anyway, so if a customer comes in with it tell them to return it and just buy proper material. It’s what I do.