
HI,
I have a GSD and have bred them and been owned by them for years ;-) I only have 1 bitch left now, but she is dominant and some would say disgusting:-0 She has just turned 6 yrs, not that age matters, and will roll in literally anything!!
Especially other dogs poo, her own poo, foxes poo, dead rodents, rancid fish, you get the picture, she'll roll:-( I have found that it is to reinforce her status. She is a great stalker (she'll be on crimewatch soon) She loves to stalk magpies, and has unfortunately brought one down, dont know how she did it!! foxes, cats, and basically anything that moves. I know that she does it to mask her scent and when ever i bath her, the first thing she does is roll in .............you've guessed it...........undesirables!!! All I can suggest is, live with it! You cannot stop a dogs natural instinct all you can do is deal with it when the worst is done:-( ie, like other suggestions on here, cover in tomato sauce before bathing so that it gets rid of the smell.....before the next session. Try to reprimand and they will do it anyway, when they think that you arent looking! Only other suggestion is keep on a lead, but this is nearly always impractical. Sorry i cannot find the answer that you want, but i also own a Briard and he doesnt show any inclination towards this behaviour, only the GSD:-)
Jo