Good points MDW - There is simply no easy way. Digging trash comes with the territory, plain and simple. No matter how proficient you become, or what kind of machine you use, you will always dig trash.
And much like the leading home run hitters in baseball typically lead in strike outs also, those who dig the most will have the most finds [and the most trash too].
Having said that, as you go on, you do get better at deciphering what the machine is trying to tell you, and seperating some of the bad from the good.
Practice - And there is no better way to learn the ways of trash that to dig it.
The key is to remember it.
Also try to vary your hunting areas. Get discouraged, move on.
Personally, I don't use all metal, as the constant iron bloops are distracing to me.
I hunt in jewelry in woodchip parks, and coins or custom in lots and fields.
The same things do show up, yes. A quarter would give the same signal in all metal mode as in coins.
All metal simply means just that - Anything metallic will cause an alert, like in days of old.