Air/ fuel tuning

can anyone tell me anything you can look for with spark plugs when driving on street and just using pump gas.
a lot of people say too hard to read anything

In years gone by you could read how the engine was running buy looking at your sparkplugs, but with the way todays gas is formulated you can't use your sparkplugs as a guide


I read my plugs on pump gas. You can do it if you know what you are looking at.