When I hunt parks and other public spots, many of the silvers I dig are deep and on-edge. I have dug silvers that had gouges from other hunter's diggers hitting them and knocking them sideways. Don't be afraid to dig those funky, uneven, bad FE-CO signals. Some of them can be silvers missed all these years. Pay attention to exactly how the it sounds, how it pinpoints, how it responds, then note what you dug. You'll be a master at it soon and digging coins nobody else would touch!
I want to give you an example from Friday. I had to travel to a town I used to live in, so I decided to get in some detecting while there. I decided to hunt one of my old hot-spots. A Buddy an I pounded the heck out of this place 20 years ago, and I guess we did a pretty good job, but we didn't get it all. Last target was pretty funky. The VDI (in high-trash) was really jumpy and kept jumping from 01-45 to 01-50, 12-38, 10-48... You get the idea. It spent a lot of time up in 01-45 spot though. When I tried to pinpoint, the signal just kept getting stronger as I moved away from the target in one direction. I changed to a Fe-COIN and it was still there, still jumpy, but it spent a lot of time around 12-45. There was a lot of iron grunting around the spot too. What it was really acting like, was a large iron rod, pointing slightly upward in the ground.
Here is why I dug: Even though the VDI was all over, I was getting a solid TONE in the exact same spot every time. It was better one way than the other, but still there. There was something in pinpoint at the exact same spot as the high-tone, even though the target got stronger as I moved away. This combination should always be dug!
That was in the hole, 8 inches deep! Although, I initially dug a 6-8 inch wide plug and didn't get it. The pinpointer indicated in the bottom-side of the hole, so I dug out that side and found the target. Even though this should have been an easy, obvious target, here is what I think was going on.
1- this was deep at about 8 inch. That is too deep for many detectors, including the 1980's detector I last hunted this site with.
2- this WAS next to iron. I didn't dig it out, but it is what kept drawing my pinpoint away from the target.
3- I am almost positive this was on-edge in the hole. Highly angled and on-edge coins always pinpoint away from the coin. The deeper they are, the more it throws off the pinpoint. I think it being on-edge is also what was causing a lot of the signal jumpiness. It was getting some of the whole-coin signal, and some the on-edge signal, and a little of the iron bleed-through signal.
Now, I was expecting just large iron but I felt that IF it was a coin it would likely be a silver dollar. Dollars read on the FE-01 line in high-trash, but on the FE-12 line in FE-Coin.
Hopefully that will give you a little insight into how to be analyzing and thinking about those not-perfect signals you hear.