claiming that certain people are cops/snitches/etc. *without producing evidence* is often an easier way to attack people's legitimacy than making a political argument, because arguments can be contentious, resting on assumptions & values that aren't "agreed upon" the way that "cops ruin social movements" is. it's also quite popular with actual cops & snitches, who use it to deflect suspicion from themselves.
don't copjacket or snitchjacket. there can be good reasons to be *suspicious* of people, to investigate, ask pointed questions, or preemptively keep your distance. but the shitty truth is that most of us are capable of all kinds of fuckups without being on government payroll.