Are you talkin' the CC or Stardust/V2/V3? Have you set your voltage appropriately for your clearo's resistance?
My experience with the Stardust V3 (2.4 Ohm) has been excellent at 3.7V on an Ego C Twist. However, if I go above 4v the hits are harsh and a bit of a burnt taste.
The CC wasn't so good for me. I believe the short wick doesn't replace the juice into the coil fast enough for my style of vaping. I take long slow draws to maximise the vapour in each toot.
Both the CC and Stardust V3 can give harsh hits if the voltage is too high or if you draw too hard.
Hope you sort it out. Clearos are a great alternative to carto tanks for a bit of extra flavour IMHO