  Scalars in AdS${}_{d+1}$ with squared masses in the Breitenlohner-Freedman
window $-d^2/4 \le m^2 < -d^2/4 +1$ (in units with the AdS scale $\ell$ set to
1) are known to enjoy a variety of boundary conditions. For larger masses $m^2
> -d^2/4 +1$, unitarity bounds in possible dual CFTs suggest that such general
boundary conditions should lead to ghosts. We show that this is not always the
case as, for conformally-invariant boundary conditions in Poincar\'e AdS that
would naively violate unitarity bounds, the system is generically ghost-free.
Conflicts with unitarity bounds are avoided due to the presence of unexpected
pure gauge modes and an associated infrared divergence. The expected ghosts
appear when the IR divergence is removed either by deforming these boundary
conditions or considering global AdS.

High Energy Physics - Theory;General Relativity and Quantum Cosmology