I’m coming in a bit late on this, but just came across the thread and have a few thoughts....
It might be hard or impossible to tell the difference between individual hand-cut and machine-cut M&Ts, but that’s not the whole story. One joint doesn't make a piece of furniture.
Hand tools have their own “logic”. There are certain operations which are easy and straightforward for them, and others which are more difficult, time consuming and "illogical". Machines have a somewhat different logic. If you make the decision to use predominantly hand tools while still hoping to be efficient then this is going to effect everything you do, from the design and timber selection onwards. It’s not usually a question of thinking a piece up without regard for how you’re going to make it - the methods open to you are a huge part of the design process. A design to be made with hand tools will, in a project of any complexity, usually end up quite a bit different to how it would be if you were intending to mostly use machines.
Producing good work, relatively quickly, with hand tools is possible (except for initial ripping and thicknessing), but one has to approach it differently. Accuracy for it’s own sake goes out the window, things are only perfectly straight, square, flush or smooth where they have to be. You quickly find the true worth of the face side, face edge system which enable small errors to accumulate in places where they don’t matter. The rule “if it looks right it is right” comes into it’s own, because the skill is more about juggling imperfections so that the eye doesn’t notice them, rather than trying to be geometrically correct.
These sort of factors may be quite subtle but put them together and they are less so. Work that is made with hand tools, and with hand tool logic rather than machine logic IS, to my eye, different in character to work made with jigged machines, and the more detail you add, the more different it becomes. Looking at Sidney Barnsley’s chip carved hay-rake tables in the Cheltenham Museum it’s hard to imagine them being made by machine. And that is a big part of their appeal - they feel (to me anyway) more personal.
Another approach to hand tool use is that of David Charlesworth who seeks to equal or exceed the accuracy of machines with hand tools - 1 thou shavings etc. I’m not anti this at all, and it’s great to see people pushing the envelope in this way. However it’s worth at least being aware that it has very little to do with how woodworking has been done historically. One doesn’t need extreme accuracy to make lovely things...
I have found that clients’ understanding about what “handmade” means is very different from person to person. Some (not many to be honest) associate the word with hand tools, and would be disappointed to find their furniture had all been made with a router. Others just want to know that the furniture is individually made by a skilled craftsperson.
The one thing that really gets my goat is when importers of crappy mass produced furniture promote it as handmade. It happens a lot, and to me this is just straightforward dishonesty.