I am fairly certain that the red color in Killians is the result of some kind of coloring. Other than color, that beer was not far from a bog standard NAIL. At least Pete's had enough flavor to differentiate it from a basic NAIL.
Perhaps, but I doubt they use coloring...unless it comes from grains. We toured the Coors Brewery 3 times, and we did the special “Executive Tour” once. Killian’s was served on tap, and tasted darn good.
I have also heard the Shiner uses coloring agents in their Bock beer. But I doubt that also.
I don't really doubt either of those. What makes you think they don't use coloring?
The use of coloring agents in beer would be non-kosher. While it is possible, it would indicate a lower class of brewery. As in, we have to "cheat" to get the color right because we don't have the technical expertise to do it with grains only.
Can't speak for Shiner, but after doing the executive tour at Coors, I'm confident they do not use coloring agents.
Do any home brewers add coloring?
From their website: https://www.molsoncoors.com/node/521
It’s not the natural coloring agents made from grain (Sinamar, etc) or sugars (caramel, dark candi syrup, etc) that make beers non-Kosher but other ingredients such as lactose in a milk stout, certain additives like fruits, etc.
https://www.dummies.com/food-drink/drinks/beer/choosing-a-kosher-beer/Shiner brings a Rabbi in each year to certify they are kosher. ...but that doesn’t mean they don’t use Sinamar [made from roasted malt according to the strict German "Reinheitsgebot" (purity-law)] or other all natural coloring agent as a quality control measure. He may certify that as well.
BTW, A LOT of breweries add colorants to beer.
Consistent color from batch to batch is considered a quality standard.