I of course haven't seen your phone, so no, I have no clue how faint it might be.
When you say however, Apple's quality control hasn't been great, what you and many others fail to understand that while the newer iPhones have screens which are more durable, it's a double edged sword. To make glass more durable (meaning its less likely break in a fall), it has to be more pliable. And more pliable is softer, which can scratch more easily. Older phones didn't scratch as easily. But they had more brittle glass, so they shattered with more regularity when they were dropped.
Apple and Samsung and Google are all users these newer glass formulas, which won't break easily, but can and do scratch easily. This is why I put a good quality screen protector on every new iPhone I buy, before they even turned on or activated.
I'm glad you have now put one on your iPhone.