afaik all 3 of those methods (well, 1-click and dummies for sure) do not modify anything in the normal ROM at all - they only install a custom recovery.
That's why you are seeing the result you do when trying to use root-aware tools in the normal OS - it hasn't been altered even one bit. What is meant by "rooted" in this case is that you have gained privileges to alter the phone (via the custom recovery) - not that the "su" native binary or the "SuperUser.apk" (app) has been installed on your phone.
The "Eris Root for Dummies" thread over on AF is quite explicit about this - you just need to read the first four or five posts carefully. It's got pictures and everything.
By booting the custom recovery, you can:
1) Back up your current ROM (highly recommended before you do anything else).
2) Wipe (data/factory reset) and flash a new ROM, or
3) Perform other customizations
Normally, if you were only going to add the "su" binary and the "SuperUser.apk" app to the existing ROM (I suppose *that* is what you thought was meant by "rooted"), you could do this by flashing the "engtools3.zip" file in the custom recovery.
There is a current thread over in the all things root subsection of AF that has a link to the "engtools3.zip" file. I'll let you find it - I'm feeling a bit lazy right about now.