We study a class of homogeneous finite-dimensional Ising models which were recently shown to exhibit glassy properties. Monte Carlo simulations of a particular three-dimensional model in this class show that the glassy phase obtained under slow cooling is dominated by large-scale excitations whose energy El scales with their size l as El~lT with T ~ 1.33(20). Simulations suggest that in another model of this class, namely the four-spin model, energy is concentrated mainly in linear defects, making the domain walls tensionless in this case also. Two-dimensional variants of these models are trivial and most likely the energy of excitations scales with the exponent T = 1. ©2001 The American Physical Society.