Not Being lazy, most of it is destroyed, blown up, and ramsacked
~ @Cake_Army_Max
Just go further its basically infinite you WILL find something. The easiest way for a NON-ULTIMATE rank to get to a clean area in the nether is to do a RANDOM warp in towny and look for a place not near any towns... then make a portal there and start your search. If you don't want to do that just go in one direction from your town portal a few thousand blocks in a straight line should not take you longer then 15 mints to get super far away.
Both towny Alpha and Beta are limited to what I believe is a 5kx5k area, so you can say it's infinite
~ @Empoleon_master
This is not true... it is infinate, however the random world generator starts glitching out when you reach: The world's usable size is 60,000,000 x 60,000,000, and the nether is exactly the same size. But due to the 1:8 ratio between the two worlds, portals in the nether only work within a square of 7,500,000 x 7,500,000 (but it is still 60,000,000 x 60,000,000 big).
Having to travel through these overly mined out areas in the nether is increcibly dangeous.
~ @weewoozesty
It is not anymore dangerous and probably less dangerous then traversing a lava lake really.