Glueball mass spectra and other issues for supergravity duals of QCD models

We derive WKB expressions for glueball masses of various finite temperature supergravity models. The results are very close to recent numerical comput ations. We argue that the spectra has some universality that depends only o n the dimension of the AdS space and the singularity structure of the horiz on. This explains the stability of the 0(++) glueball mass ratios between v arious models. We also consider the recently proposed nonsupersymmetric mod el arising from the type 0 string. In the supergravity limit of this model, the heavy quark potential has an effective coupling with 1/(log u) behavio r in the UV. Unfortunately, the supergravity solution implies that the heav y quark potential is still coulombic in the infrared, with an effective cou pling of order 1. We also argue that the type 0 supergravity background sol ution does not have normalizable glueball solutions.