We investigate the impact of gas evolution on the expected yields from deep Sunyaev-Zeldovich (SZ) effect surveys, as well as on the expected SZ effect contribution to fine-scale anisotropy in the cosmic microwave background (CMB). The approximate yields from SZ effect surveys are remarkably insensitive to gas evolution, even though the observable properties of the resulting clusters can be markedly different. The CMB angular power spectrum at high multipoles (l ≳ 2000, ≲ 5') due to the SZ effect from clusters is quite sensitive to gas evolution. We show that moderate-resolution (≤ 1') SZ effect imaging of clusters found in deep SZ effect surveys should allow a good understanding of gas evolution in galaxy clusters, independent of the details of the nature of the gas evolution. Such an understanding will be necessary before precise cosmological constraints can be set from yields of large cluster surveys.