I wrap my meats tightly in plastic wrap first, then put into the FS bags.  I take the meat
out  of the bag before thawing.  That way the meat juices do not get on the FS bag..  I did not know the company always said they could be reused.  I got a lot of flack from someone on another site when I gave out that tip.  Was really put down for reusing the bags.  Sigh...