BERLIN — Germans have no trouble agreeing that the graffiti covering many of the nation’s commuter trains in a most un-Germanic scrawl is intolerable. But what they cannot agree on is the main railway operator’s proposed cure: small drones to patrol the rail yards by night.

While the tiny remote-controlled helicopters, equipped with cameras that officials hope will allow them to catch the graffitists on the spot, are only entering the testing phase, the debate is well developed in a country where clandestine surveillance is a strongly emotional issue.

The railway operator, Deutsche Bahn, said its miniature drones would be used to patrol the depots and train yards on its own property, not in public spaces, in an effort to combat a problem that costs the company around $10 million a year.

But German unease over unauthorized prying, rooted in memories of Nazi-era denouncements of neighbors and East Germany’s omnipresent secret police, runs deep. And it often leads to conclusions or requests that outsiders might regard as paranoid — deep enough, for example, to have forced Google to bend its rules, allowing Germans who objected to images of their homes being published on the Internet to request they be blurred.