  The high spatial resolution of the Hubble Space Telescope (HST) has led to
tremendous progress in many areas of astronomy. The ability of the HST to peer
into the bright inner regions of galaxies and distinguish between globular
clusters (GCs) and background objects has been particularly beneficial to the
study of clusters. But the very virtue of the HST that has been an asset to
such research can be its pitfall if the consequences of superior angular
resolution are not considered in detail. Recent HST studies show a small, but
consistent, color-magnitude correlation in the metal-poor halo GCs of nearby
galaxies. This `blue-tilt' has been interpreted as a mass-metallicity
relationship, implying self-enrichment in the higher mass GCs. We show that the
`blue-tilt' is likely the consequence of a small, but measurable with HST,
mass-size relationship in GCs. The combined effects of Poisson noise and
surface brightness fluctuations can explain other apparent correlations of the
`blue-tilt' with environment. Some HST based studies have similarly suggested
that the mean metallicity of the blue, metal-poor, halo clusters increases with
host galaxy mass, indicating that GC metallicity is linked to the size of the
host galaxy halo. We show that this correlation is also likely due to the
effects of GC size in high resolution HST images. We also point out that the
presumed fundamental plane of GCs itself varies with galactocentric distance
due to GC size trends and ultra compact dwarfs may simply reflect the tail of
the globular cluster distribution.
