  If the large-scale galaxy distribution is filamentary, as suggested by some
observations and recent hydrodynamical simulations, then lengthwise views of
filaments will apparently produce compact groups (CGs) that are in reality
stretched out along the line of sight. This possibility has been advocated
recently by Hernquist, Katz \& Weinberg (1994). Here, we propose a test for
this hypothesis using X--ray emission from CGs. The observable quantity $Q
\equiv L_{x} a_{p}^{3}/L_{g}^2 T_{x}^{1/2}$ should be proportional to the axis
ratio of the group, $a/c$, where $a$ and $c$ are the long and short axis of a
prolate distribution, $a_p$ is the radius of the group projected onto the sky,
$L_{x}$ is the bolometric X-ray luminosity, $L_{g}$ is the group blue
luminosity, and $T_{x}$ is the gas temperature. We find that the distribution
of $Q$ is consistent with the notion that many spiral-rich CGs with unusually
small values of ($a/c)$ are frauds, i.e. that the values of $Q$ are anomalously
small. An alternative possibility is that CGs are gas-poor relative to rich
clusters; however, this can be tested using the Sunyaev-Zeldovich effect. If
the groups have a normal ratio of gas-to-total mass, but are simply stretched
out along the line of sight, a Sunyaev-Zeldovich signal should be detectable.
