Rescued aggressive dogs

I've seen from a few posts that there are some of you that have rescued dogs that have (or had) some aggression issues, like I do. I'm hoping maybe we can trade some info or ideas that maybe might help some of the others of us?

I've had Willie for about 19 months now and while we've made tremendous progress, there are still some areas that we haven't. And I'm wondering if I'll ever conquer all of it. I love him to pieces, so he's not ever going anywhere, but I wonder if I'll ever be able to completely trust him; and I worry about what will happen to him if anything happens to me.

He's a Shih Tzu mix with a very thick & fast growing coat, so I have necessary & extensive grooming needs with him. I have to take him to the vets every few months to be sedated so they can shave him down for me. I couldn't brush him at all when I first got him, but now he loves it over *most* of his body. In between shavings, I try to keep his eyes trimmed 'cus he has probs with dry eye.

Just last night we had a little "episode" when I was trimming his face, tho. While he doesn't like it, he lets me trim around his eyes as long as I have a really good treat in my hand. It's kinda funny, 'cus he'll sit there and his little lips start snarling up & he growls, but he won't do anything as long as that treat's in my hand, so I giggle at him a lot & praise him a ton while I'm doing it.

Last night I tried to trim his beard, tho, 'cus it's getting longer & messy. I got two good clips done, but on the 3rd one, he blew. He lunged & snapped at me & the scissors, growling, snarling and the whole bit, then sat back, still growling & staring at me. I sat back for a couple of minutes, then started trying to get the scissors back by his face, but he kept ducking away, even tho I had the treat. Finally I put the little ham cube right on the scissors and just held it there until he finally took it. A couple of times doing that, then I was able to "brush" his head hair with the scissors again, then took a couple of snips up there, then I let him go.

I imagine that some of you also go thru the same stuff, so hopefully we can help each other out here.

And please don't tell me to just dominate this dog - been there, done that. Even a very pro trainer has, and it doesn't work with him.