One thing I've learned is that not everyone understands a persons interests or desires. Add in that some are not sentimental and quickly you see how an entire collection spanning years, possibly decades could be passed off without much regret.
On the other hand financial difficulties and the owner not documenting what each peices approximate value was and you can see how this could easily happen.
Look as a public service I'll help you or any other member here out when this happens and take everything you have off you hands for $1 each plus postage