What a pleasant surprise to find you here @PrashanthSarda!
Dear commenting systems have still a long way to go in order to combat Spam completely. And when it come’s to Blogger’s commenting system, it is the worst amongst All. I have sent several reports to Blogger team complaining about their poor Spam protection system but the bigger you get the harder it becomes to respond to customer queries.
Disqus is surely a good choice when it comes to moderating comments on an auto-pilot mode. But when it comes to word filter, it is really impossible for any comment system to block it because there are several ways to type a word. I can write word as “Word” or “w0rd” or “\v/rD” or even "W0r|)"
It is really impossible to stop spam by simply filtering common vulgar words, unless you moderate manually and this is what I do on all my sites. I can no more rely on any plugin or tool for differentiating between a spam and a comment.
Spammers find and invent new ways to abuse a system and the only good way to stop them is to do the moderation manually rather setting it on auto-pilot mode.