what is going on with supernatural no more laughter times and there are flaws now how could Bobbie be possessed in season 5 if he knew aboout them so well why didn't he protect himself with the tattoo like Sam and dean?

Ah well, there's still laughter, it's just a little more scattered because of, well, you know
The Apocalypse.
And Bobby isn't a tattoo kinda guy. Maybe the got him in his sleep when he didn't have his charm on. It's the Apocalypse, the demons are getting smarter.

Watch S05ep07 and you will laugh a lot. I think Bobby is too worried about both Winchesters to watch his own back. He's still alive and tutoring them, ain't he?