There are some effects you can notice, like completely disappearing from index, '31 paragraph', various filters...
if u website get removed from google's index then its a danger sign for you, and you can consider that situation as blacklisting on Google.
Banned is easy, you site is no longer indexed nor has backlinks or pagerank showing. Penalties there are various and are much harder to tell.
it hard to tell anything right now. Google SEPRS are changing so much its hard to tell if it is something wrong with your site or just a tweak at Google.
Well is there any kind of tools that we can go ahead with. It will make the things better for the beginners. Some sort of tools that can warn us.. hmmm tough one and i think google must begin with these kind of simple web based tools. Which can warn you ... its better to get warned then simply get banned straight-a-way.