Deviations in Paczinsky lightcurve is the clearest signature of companion orbiting the lens star. The problem is these deviations can be very short time duration (~ 1 day ), so it's easy to miss them.
Microlensing surveys now product lot of data ( ~ 1800 events this year ) so check by eye all events is very hard. I'll present a very fast software which check for us what is going on each day on all events, to see which events needs to be observe.