I think seeking the advice of a trainer is really the best option here too. Also, I know you said you play with him, but how much exercise is he getting? Your mantra here should be, "A tired dog is a good dog!" 8-month-old GSDs can require a lot of exercise.
Please, please do not use a shock collar on him. Most trainers I have worked with do not recommend them for biting/mouthiness issues because they can escalate the behavior into aggression, particularly if you are inexperienced with them and your timing is less than perfect. I'd say that is true of most strong aversives, actually--pulling on his ears? Yikes, that would get me bit by my mouthy dog in a heartbeat! I agree that most of the methods you mention will just make things worse. Even the soap on your arms...not only does that sound horrible for your skin, but I know my dogs get upset if I have scented things like soap or lotion on my skin and want to get it off!
A couple of things to consider as you set things up with a trainer...do you ever give in and reward him for nipping you? In other words, when you're, say, trying to put on your shoes and he comes over and tries to get you to play, do you ever grab his toy and play for a few minutes just to get him to leave you alone? It's an easy temptation to give in to, especially if you're running late for work or something and just really are not in the mood, but if you ever do that, you're encouraging him. At this point, play should only happen if he's being polite and you initiate it, or if he asks politely (for example, if he comes up to you and sits in front of you with his toy in his mouth, reward him by playing with him even if you don't really feel like it; he needs to know what is good as well as what is bad!). So if you ever, ever even think about doing that, stop! And keep in mind, pushing him away or holding him down can seem like wrestling to him and also be a reward.
Next, ignoring him is probably the safest thing you can do. Any attention is fun for him--dogs play a lot rougher than we do (and getting rough enough to deter him can lead to biting, as I said above), and clearly your verbal corrections aren't helping. Since turning your back doesn't work, I'd suggest a "time-out"--if he gets rude, you immediately (and I mean immediately) send him to his room, as it were. Some people use the crate for this (if he's crate trained), but since it's a negative thing, I would probably set up an x-pen or gated off area in a room he can't do much damage to, like a laundry room or bathroom. You do this silently, and walk away completely so he can't see or hear you. Leave him in there for 5-10 minutes, then take him out--but if he gets rude again, you immediately return him to the room. If he's in a playful mood, you might spend a few hours doing this one evening, but hopefully it won't take him too long to get the idea. And you need to do this every single time he nips you. To help with this, confine him in a "safe" space (not his time-out room) like his crate or bedroom when you know you're going to do something that will excite him like putting on your shoes. Try to manage him so that he only has the opportunity to nip when you have time to train.
Basically, you need to try to minimize his opportunities to practice this behavior, while rewarding good behavior (whether it's playing when he asks politely, or simply letting him hang out in the room with you while you watch TV--being with you is a reward in itself). As far as the time-outs go, be sure you're being firm and matter-of-fact but not emotional or loud (talking to him as you take him to his time-out room, for example).
Also, and I'm going to bold this because to me it's probably the most important thing: This must be done in conjunction with him getting plenty of exercise, mental stimulation and positive attention from you. You're going to be fighting an uphill battle if he has too much energy or is bored, and probably no training method is going to get you the results you want. I'd also recommend practicing NILIF, or "nothing in life is free" if you're not already--basically, before he gets any food or treat or other fun thing, he has to do something good (a sit/stay before dinner, for example...it doesn't necessarily have to be something big). This will help establish you in a leadership role and as the one who is calling the shots.
Anyway, there are lots of ways to handle an issue like this and so please do consult a trainer. The strategy I outlined here is just to help get you through until you can get someone to assess your individual problem and help you develop a more personalized strategy.
The rowdy dogs:
Hector-2 y/o GSD (mix?) rescue
Scooter-12 y/o ACD/Border Collie mix
Bandit-8 y/o ACD
Wooby-14 y/o ACD
Abutiu "Abi"-ACD puppy and hopeful future SAR dog!
Last edited by RowdyDogs; 12-14-2012 at 02:00 PM.