I have had some less than stellar results with commercial glazes, but those are few and far between.
The makers do a whole lot of testing to ensure a good, consistent product. By doing so, they keep customers happy and stay in business.
Because of this, I would probably trust a commercial glaze more than one I made. I simply don't have the time and resources to test and retest it as much as they do.
Also, any of the aforementioned less than stellar results, were probably due to an error of my own. They just didn't fit into my standard firing schedule along with my usual suspects.
So I can't say I would chalk it up to an inferior product. It could be that the glaze didn't work well on your clay body, or that your firing schedule caused issues. A lot of factors to take into consideration, and testing that can be done.
- vinks likes this