Hold on, but I kinda see it the opposite way... if you only do your best work when someone's watching, then you're not really a professional, you're just a performer. That homeowner's comment is a good kick in the pants, but it shouldn't take a customer saying it for you to do the job right the first time. I get that landlords are cheap and it feels like wasted effort, but you're the one who has to sleep at night knowing you left a glaze on there that's gonna cause problems down the line. Plus, that "nobody will inspect it" thinking is how you end up with a reputation that follows you around faster than any good job does. Honestly, cutting corners on a flue is dangerous, not just sloppy, and that's a line I won't cross no matter who's paying.

Was it the DiNozzo energy that hooked you or something else? lol

Careful with a chisel on glazed flue, that can crack the tile real easy.