Following every day eBay, I noticed that although in worldwide sales there are numerous B&O products, most of them end up without any bid/sale.

Is it just my idea or anybody else noticed it too?

I haven't really noticed - except when the starting price is totally off the scale, or the item is pickup only in Greenland, or impossible in some other way... or mislocated/misspelled bad enough that not even one eligible bargain hunter can find them.

Shocking as it may come to some sellers, there are items with "Bang & Olufsen" printed on them that actually are not worth much

For some commodities, like cables, there are so many sources that they just may not get sold even at the right price. I would expect the most common Beomasters in bad condition, for example, to fall in this category as well - if it's junk, even the junkers might not bother when better specimens are everywhere for the same shipping cost.

Probably it is the fact that the majority is as you described. However, I noticed that people have really increased prices in many items which probably is not worth anymore and on the other hand too many cables, catalogues, user manuals etc... But stil there are some good opportunities!!!!