I know, it's one of those questions without a real answer but I wanted to ask for input if anyone has any. Are there any criteria that makes or breaks whether you use a shop? It's common knowledge to stay away from the dealership obviously, but I just had such a bad experience with a local shop I'm wondering what more I could have done or known to have avoided it.

 

Here are my criteria as not all dealer service centers are bad, and not all independent mechanics are great:
1. Value. Obviously indy's will be much cheaper until you get the "too good to be true price", that's when it's time to look elsewhere or even the dealer. In some specific cases, dealer may be a better route for things like transmission fluid flushes (for the Toyota sealed transmissions) and modules that require VIN coding (like LS's ABS module).
2. Mechanic knowledge. I've literally had a person call themself a "mechanic" but didn't know Toyota uses ATF fluid for their hydraulic power steering. Makes me wonder if they put oil in the oil cap....... Find a mechanic that knows Toyota/Lexus or even better if they know the quirks of your model.
3. Reviews. We are in a new age, reviews are everywhere, might not be 100% accurate but it's a good starting point. Find a mechanic with decent reviews then go talk to them, it's pretty easy to see if they know what they're doing or just winging it.

 

Thanks for the reply, Lexuswiz. I'm supremely miffed, but more at myself since I think I could have avoided my troubles if I wasn't in a rush. I didn't get more than one quote/opinion and went with a (formerly trusted) mechanic, but he wasn't the one who did the work. Your point 2 is spot on and I guess it's always this way. Shops need warm bodies I suppose and the first schlub who shows up that knows how to do an oil change is assumed to be a 'mechanic'. I guess an expectation of craftsmanship and knowledge means I must officially be getting old.
I'll be heading to the dealership to get a once over for peace of mind for the botch job I got.

 

Don't forget one of the most important advice about finding a mechanic: word of mouth from family, coworkers, and neighbors.
I found my current indy (independent mechanic shop) after asking one of the co-workers who took his Toyota to get serviced. So far it has worked out really well and the prices are 50% less than the Lexus dealership. The shop specializes in Toyota/Lexus and has been in business for 30 years. The guy who owns it is doesn't advertise widely or buy ads online, but he's good at what he does and has built up a steady business from repeat customers. If you ask around and get good recommendations from others, make sure to let others know.

Otherwise, if you have no other choice and need to get something fixed quick, you might want to go to Toyota dealership as service is the same, but the costs are less than Lexus stealerships.

 

Echo reviews - would add use google reviews. I found my mechanic that way. If a shop has many lengthy positive reviews (not just "Great shop!" those are bull****) but reviews that sound like that are from real people, I'd say they are worth a shot.
Moved to a new city and found my mechanic that way. Not saying it's foolproof but I couldn't be happier.