They are rare-ish: it uncommonly drops from an easy-to-kill robot.

There are much, much, much more rare items in the game. It's hard to pin it on an either/or side of the scale. "Rare" also implies "valuable", which is not always the case. There are also other factors at play, like how long some people have been playing this game. Is something you might run across one time in playing a steady week considered rare when there are still things in this game I haven't seen after a decade that I know exist?

I hope that helps.

In terms of actual rare drops in this game they are not rare at all. But, rare or not, they currently are worthless and never used by anyone. Stockpile 10 of each spoofer for "later" and ignore collecting any more.

They sell pretty well at stations, so its worth picking up even if only for that.

Hardly anyone uses spoofers because the ships you'd actually want to put them on (Behemoths, Tridents) don't have the port for them.