Well.
Bought some cigars last summer, stored them at what should have been the right RH (around 66 %). While I was on the road, they were in my travel humidor, at home they went into the glass jar.
The ones I smoked right away smoked fine, but by september, the others were already showing the sick taste.
I found
this link, which leads me to believe that the cause of the problems might be that the cigars are sealed in, without any air circulation. This sort of makes sense - when I started using the glass jar (and the tupperware humidor), I was new to smoking cigars and very excited by it, so I kept opening the containers to look at the cigars. This way, the cigars got plenty of fresh air.
In the past two years or so, the obsession has died down somewhat and the only time I open the jar is when I want to actually smoke one which doesn't happen all that often. In the mean time, the cigars are suffocating.
For the past couple of months now, I've been opening the containers (glass jar, tupperware box, cigar caddy travel humidor) once a week (on average) for about half an hour. Hopefully, this will help. Judging by the RH decrease upon opening, he tupperware box and the travel humidor air out nicely while the glass jar not so much. Something I still need to look into.
At this point, I'd also like to ask you for advice on small (and preferably inexpensive) humidors. At the moment, a sizable humidor is out of the question as I'm moving into a smaller apartment, at least for a while, and my financial priorities also lie elsewhere.