Yes, one should definitely avoid trading in exotic pairs. These pairs are way more less liquid than any of the majors and the minors. The reasons behind this are-
Huge Spreads- The difference between the bid price and the ask price for exotic currency pairs is way too high as compared to the major and minor currency pairs. The spreads can go as high as 600 to 700 pips.
High volatility- These pairs are so volatile that if you observe the market of exotic pairs for even one minute, you will observe a huge difference. It can take a huge jump of some hundred pips in seconds even.