Was trying to cure disease (plague) at healers from various locations (non-big cities) like in Ysigarth, Tir-Taleth, but the healers keep failing even after 3 attempts. Plague is not really a potent disease so why the high failure rate? With the Outlander cabal and wanted flag, these healers should perform just as good as the other big city healers.

Bug?!! Or gameplay?

Healing success has nothing to do with city-or-not-city.

You might see an effect based on the healer's level for certain abilities, but it's not consistent with your observations. (For example, Tir-Talath's healer well above level 51.)

valguarnera@carrionfields.com