FWIW, I have also checked into hotels that don't check my passport (or look at it) but the vast majority of them do check and write down the info. Especially in Nordic countries I find people do check the insides of passports. Six days ago I checked into a hotel in a Nordic country and they checked both of my passports and looked carefully at the photos, in sharp contrast to the rest of the world.

I think, especially for a foreign woman in small Norwegian places in the 70s, that people would check passports.

And yes, 70s passports were easier to fake. Still, if she had multiple fake passports, as well as with the circumstances from the article, I have a feeling that this isn't just some independent person playing spy. Using a fake passport to escape the GDR makes sense: that's something a non-spy would do. Using multiple fake passports to check into hotels in a foreign country, meeting with Germans in Norway, evading detection, then getting killed by someone who knew what they were doing? That doesn't sound like a non-spy.

But yes, the problem here is that if each of my assumptions has a 10% chance of being wrong, and I make 5 assumptions, my final categorization has about a 60% chance of being correct. Still, it can put the search on the right track: searching a small list of people (short female aged 25-40 that was a USSR, GDR or BRD spy in the year 1970 with gold teeth and brown eyes) makes the search a hell of a lot easier.