  The number of astrophysical sources detected by Advanced LIGO and Virgo is
expected to increase as the detectors approach their design sensitivity.
Gravitational wave detectors are also sensitive to transient noise sources
created by the environment and the detector, known as `glitches'. As the rate
of astrophysical sources increases, the probability that a signal will occur at
the same time as a glitch also increases. This has occurred previously in the
gravitational wave binary neutron star detection GW170817. In the case of
GW170817, the glitch in the Livingston detector was easy to identify, and much
shorter than the total duration of the signal, making it possible for the
glitch to be removed. In this paper, we examine the effect of glitches on the
measurement of signal parameters and Bayes factors used for model selection for
much more difficult cases, where it may not be possible to determine that the
glitch is present or to remove it. We include binary black holes similar to
current detections, sine Gaussian bursts, and core-collapse supernovae. We find
that the worst effects occur when the glitch is coincident with the signal
maximum, and the signal to noise ratio (SNR) of the glitch is larger than the
signal SNR. We have shown that for accurate parameter estimation of future
gravitational wave signals it will be essential to develop further methods to
either remove or reduce the effect of the glitches.
