[NoggenFogger]

I've had the same problem in the past for various reasons.
1st, make sure they are turned on by clicking the tracking icon next to your minimap (the one with the magnifying glass icon) and checking the "Track Quest POI's" option is selected.
Next, you can try right-click on the minimap, go to Transparency and make sure the Quest Blobs are set high enough so you can see them.

If all else fails... you can do what I did, and reset the Carbonite saved variables altogether.
To do this:
-Exit WoW completely.
-Open the WoW WTF folder on your computer (C:\Program Files\World of Warcraft\WTF)
-Navigate to C:\Program Files\World of Warcraft\WTF\Account\*YourAccountName*\SavedVariables
-Delete the files Carbonite.lua.bak & Carbonite.lua (You can simply rename them if you don't like the idea of deleting)
These files will be recreated by Carbonite automatically the next time you login with the Carbonite AddOn enabled.

This will reset all of Carbonite's settings to their defaults, which has blobs (among other things) enabled.

Hope this helps!