Had an inspection of a house I'm interested in today, and found this when looking at the sub-floor space in several areas:
http://i40.tinypic.com/2mnnknl.jpg
To me – a complete novice in structural matters – it looks like moisture in the particleboard flooring; it didn't feel wet per se, however, nor was it present in any one clear area. Rather there was a dozen or so patches all around, not correlated with bathrooms above or anything like that. No visible mold.
Any opinions / thoughts on what it might be and if it is a cause for concern?