P.S. To be a little more accurate, not all of those 17 reports on the Wireless Rd. bird from Nov-Dec 2015 were independent observations. Some were by people birding together who gave identical comments/photos in their reports. From a quick glance through, there were about 11 independent observations in the series, one of which (by Shawneen Finnegan and Dave Irons on 29 Nov 2015) includes a description of typical Tropical Kingbird vocalizations.
If anyone has bottomless energy to dig into this, you might consider making a table like in the attached graphic, to summarize the evidence for each *series* of observations of a single or flock of reported Tropical Kingbirds at a given location. This is rather tedious, and some interpretation is needed to handle cases where people have posted checklists for personal/GPS locations rather than using an eBird "hotspot."
But personally and probabilistically, I feel like I've looked at enough of these reports to establish that there is no reasonable cause to doubt that at least 90% of Tropical Kingbird reports in our region can safely be treated as such, for any reasonable use of these data in an aggregated analysis.