  Assessing the presence of chemical, biological, radiological and nuclear
threats is a crucial task which is usually dealt with by analyzing the presence
of spectral features in a measured absorption profile. The use of quantum light
allows to perform these measurements remotely without compromising the
measurement accuracy through ghost spectrometry. However, in order to have
sufficient signal-to-noise ratio, it is typically required to wait long
acquisition times, hence subtracting to the benefits provided by remote
sensing. In many instances, though, reconstructing the full spectral lineshape
of an object is not needed and the interest lies in discriminating whether a
spectrally absorbing object may be present or not. Here we show that this task
can be performed fast and accurately through ghost spectrometry by comparing
the low resources measurement with a reference. We discuss the experimental
results obtained with different samples and complement them with simulations to
explore the most common scenarios.
