Quara scouts are in several places in tibia, there is a grotto in liberty bay, but you are probably talking about it in your question, I will not mention all the smaller places, only the most important and the best ones in my opinion.
the first though not too big place but suitable for the lower levels is in the north of svargrond HERE and HERE this place is called Hrodmir Quara Scout Caves
Bigger and better place is Malada one of the forbidden islands it has a vast underground with quars, the only problem is that they are quite scattered and a lot of time is wasted running from place to place.
Last and best place is West of Oramond the place is intended for higher levels, but it is also the best place to hunt for quars, although it has a few drawbacks, there is no Quara Mantassin Scout and spawn quar is not regular there, they appear there from time to time in the form of an hourly raid