You could always ask for build pictures I do them for customers from time to time. Most fixed blade's are hand made . Some of the tactical folders are cnc made but they still bring in the $1000's. Price some of Todd Begg's knives they use a lot of cnc machines. But most knifemakers on here are to poor for a $100,000 cnc machine at least I am lol

Several ways to tell, but it comes down to the integrity of the maker. A machine produced knife may have better symmetry, cleaner grinds, than an amateur hand made knife. A hand made knife may have some minor variations or points of error. If it looks too clean, and google doesn't tell you anything about the maker, then it's likely a blank or a machine produced knife.

FWIW I call a "blank" any knife that you can buy from a supplier with the bevels having been already ground and polished.

My personal opinion, as the president of the Texas Knifemakers' Guild and a voting member of the national Knifemakers' Guild, is that the most important thing is full disclosure. If I say I "made" a knife, then I at least ground the bevels and installed the handle. If I put a handle on a blank, it is dishonest to say I "made" it. On the other hand, if I put a handle on a blank, tell you it's a blank, and price it like it's a blank, then there's no problem. If I CNC a knife, which as Mike said, most of us can't afford to do even if we wanted to, I may or may not say I "made" the knife, but I can't say it's hand made. If I have a company with CNC machines contracted out to make knives after my design, I can't say I "made" it or that it's hand made, but I can sell them with good conscience if folks will buy them knowing I didn't make them. In the end, for me, it's all about full disclosure. Don't misrepresent your work. Price your work in a way that's commensurate with the amount of time, effort, and skill that went into it, and let the free market sort it out.