Is this what a flat spot on a cam looks like?

I just picked up a set of Andrews 3x cams on Ebay. They look good overall, but one lobe has a sharp line just past the tip of the lobe. All seven of the other lobes have a smooth transition over the top.

The overall height of the lobes all measure within a few thousands with my crappy harbor freight calipers, even the one lobe that looks not right.

Is this what a flat spot on a cam looks like? Did I buy a bad set of cams?

Those marks on the side of the lobe appear to be from the casting , when the cams were made . the mark on the face of the lobe would be of more concern. Could be form being mishandled however more likely to be from contamination /lube starvation in the previous engine . I reckon it would clean up with a light linish.
Radical "ramp ' on those cams - haven't seem much on Andrews cams here in OZ - just make sure they clear your tappet covers !

It was hard to get a good picture of it. The side profile picture with the two lobes side by side was intended to highlight the different shape of the lobes. The one on the right is the one that looks damaged. It doesn't have a symmetrical ramp, and comes to a point slightly to the left of the top.



Here is another picture comparing the face of the bad lobe and another normal one. The line across the face of the bad lobe is highlighted.

So when the sharp apex of the cam lobe comes in contact with the shim on top of the bucket, there should be additional friction and I would think, over time either the shim or the cam lobe will wear and this will interfere with your clearance between the two ?

Also plays in the way the corresponding valve opens and closes I guess.

You need to do some lobe height and lift comparison measurements.
It could be a slightly faulty grind ( Friday afternoon job) as it looks like the grind stone has not made a full pass and left a small ridge on the tip of the lobe.
If that is the case that lobe will read a fractionally higher lift.
When a flat spot occurs it is where the hardening has worn through which usually leaves the soft portion of the lobe pitted with a very different appearance to the hard surface.
That does not seem evident on the pics you have posted.

It does seem to have the feel of a Friday afternoon job. The surface of the oddball lobe looks fine. Used, but not bad. I took some more fuzzy pictures.

I also measured the lobes with my slightly messed up 2" micrometer. I get a pretty big variation over the 4 lobes on the cam. The one lobe that I think looks wrong is not the smallest. From left to right, I get 1.512, 1.501, 1.506, 1.504, with the 1.504 being the funny looking lobe. These cams are supposed to have 0.418 lift, so they should measure 1.518" right?

Also, running my finger over the lobes, I can feel a hint of a peak on the two inner lobes, while the opposite outside lobe (the one with the largest lift) looks perfectly smooth and symmetrical. It's likely this is just poor quality grinding.

So the seller said he'd take them back. What do you folks recommend?

Return them.
I strive to have the same things happening on all my motors separate cylinders
For balance and smooth running , and easier to tune
Like having different cylinder pressures and expecting it to preform properly
Dave

That is a damaged lobe.