Ok, so I got a Fantastic deal on a Filharm. Thing arrives with zero bevel wear. I ask seller it's history, and apparently they've been using it for 2-3 years. Hmm says I.

I shave a bit. It tugs. I check the edge, it's decent but not great. I hone and strop. Passes HHT easy (another thread on why the HHT irritates me).

I put it aside for a day. Pick it up and shave with it today. One of my worst shaves ever. Damnit says I... having a sneaking suspicion I know what's wrong. But against my better judgement, I check the edge, figure I must have just not honed well enough, and back to my honing. After an hour on my 4k bear I finally admit that I was right in the first suspicion. I've been sawing away at spine and slope with a highgrit stone because the previous owner taped the spine. No big deal, razor won't be as pretty when I fix it, but it wont take long.

So I break out the 1k to take off all the material that should have been taken off over the past 2-3 years. Task is made super-easy by the fact that somehow the previous owner blued the edge (some kind of extra glide coating I assume). I check under my scope every few passes and watch my nice clean silver envelop the blue... all except for the center. Damnit... says I, this previous owner couldn't hone for crap. So after about 30x (no joke) as many passes as it took me to rebevel at the toe and heel, I finally have a true and beveled razor... but here's the best part... the bevel at the heel is probably ~4-5mm deep... This guy guided the razor with his offhand about 10% north of center, it looks like with either a thumb or fat middle finger. It was noticable enough I can be that exact.

And because the razor was only a 4/8" to begin with the concavity wasn't noticable before... but once it's fixed, the spine sure makes it obvious. The irony is that there's no way he ever would have screwed the edges true up that much if it weren't for his using tape, which kept the spine from doing it's job while he was honing. So in the end the thing that did by far the most damage to the razor was his attempt to prevent damage to it. I am now THOROUGHLY convinced that telling newbies to tape spines is possibly the worst advice you can give. Yes, an experience honester would have been able to keep the edge true even with the tape on. But the tape effectively removes the built in level of your razor as well as amplifying any downward pressure you apply to it. I can't think of anything worse to do when you're trying to learn honing.