A "rats nest" is basically a mess of overlapping interconnected edges. You may find that simplifying the original Spline shape (prior to applying the Lathe) will get rid of it. Fewer Vertices with suitably adjusted Tangents will likely work better than trying to get the required shape by using many Vertices.
Max 2016 (SP1/EXT1)
Win7Pro x64 (SP1). i5-3570K @ 4.4GHz, 8Gb Ram, DX11.
nVidia GTX760 (2GB) (Driver 430.86).