It is quite true that plastic storage tubs can transfer unpleasant odors to plastic toys - I switched to cardboard file boxes with attached lids and bankers boxes for most of my storage needs as they don't have any glue or tape on them.
That's a good idea, as long as you have no humidity concerns!
I have used active charcoal bags to eliminate odors on items that are not easily cleaned with soap and water.
I haven't tried that before, but that seems like an interesting idea! Besides thorough washing, I've tried temporarily storing items in containers with newspaper or baking soda with some limited success.
Yeah, that book is no longer in my collection; it wasn't even old. Books are my larger collection, so I've definitely run into issues buying them online.
It's never fun when you finally find something to add to your collection but avoid doing so (or ultimately end up removing it from the collection) because of poor condition.
On this topic, another thing to watch out for when collecting and trying to preserve collectibles is excessive exposure to light (particularly light from the Sun or from artificial light sources like fluorescent lamps that emit ultraviolet light). Ultraviolet degradation can easily cause fading or changing of colours, which I think many of us have seen with white Playmobil parts turning yellowish (but it can happen to parts of other colours too). Plastic parts exposed to ultraviolet light over a long period of time can also become brittle. The colour fading also applies to printed materials as well, such as Playmobil boxes (and books since we've mentioned those several times in this thread
).