what is best way/practice to uninstall a plugin

Hi, I guess this is related to a previous post I made, but thought it might warrant a new topic.

testing of a site / theme / plugin when trying to resolve an issue.
usual steps at some point would be to "uninstall" plugins -

when we say "uninstall" do we usually mean to uninstall and remove the plugin completely from the site / host
or would disabling a plugin from the admin panel "should" provide the same results as an uninstalled and removed plugin.

or do just go through the process - disable first and if problems persists go see a doctor...umm then remove it and see.

thoughts?

cheers,
Steve