Answer:
Often, the answer is YES. Inseam lengths can be altered with varying degrees of difficulty.  Simple cotton pants are easily altered.  However, if there is a zipper at the cuff, it may require removing the zipper and replacing it with a shorter one.  On many of our pants/bibs that have cuff zippers, we stop the zipper 2" or 3" from the bottom to allow shortening of the cuff without having to replace the zipper.

However, due to the huge variety of pants and bibs offered each year, not all are made to be easily altered.