I got Shenzi free from Kijiji at 3 years old, knowing the dog had issues that was even cemented when i met the dog and she bit me. (no puncture, but there was a bruise).
I knew what I had in front of me.
A little over a year later, she is doing great. elevator, hallways, checking the mail, she is great. But she definantly has a bubble and I keep people out of it. I've started to look at it as I will not stress her out because OTHER people want her to be something shes not. She's everything I wanted (now). she cuddles, shes trained, she makes me laugh. She doesnt need to make other people laugh to make me happy.
I think if your dog is manageable and safe under your control, further training is up to you. Are you willing to continueally stress out your dog, put an ecollar on it potentially making it worse?
I have also learned to pick my battles. Shenzi does not need to like joe moron cooing over her head, but she will accept my friends into my apartment without assault. She will on her own accord spend individual time with my friends, petting, fetch, LIGHT wrestling, she initates contact with my friends. I don't force that on her, she initates contact only (its a strict rule in the house that visitors are not to approach her) but it is nice to see her having fun with someone who is not me or my bf.
Pick your battles. Its tough having a dog with issues. I gave you a lot of nonsense, but I needed to vent. I accepted she is who she is and I couldn't 'fix' her when I talked to someone about their battle and how they had reached a plataeu. This person was going to lengths I wouldn't,and stressing the dog out as a result. The dog apparently went of feed and everything. I'm not willing to do it. So I quit trying to fit her in a mold she won't fit in.