In my experience there are plenty of US shops happy to get work on a few specific widgets, typically by having a CAGE code. They aren't necessarily incompetent in the act of making a specific part, but they aren't optimized in a production sense.
A quick checklist for sniffing out shops:
1. Are they ISO? Getting through an ISO audit says something about the facility.
2. How much WIP is sitting around on a visit? With the best vendors I've worked with you'd swear they didn't do anything until you see their shipping lanes. Low WIP and busy shipping is another positive.
3. Ask to see their rework area. If they have one and SOPs for handling rework, that is a positive
4. Ask to see their documentation for current parts. PPAP, CoC, etc.
A quick checklist for sniffing out shops: 1. Are they ISO? Getting through an ISO audit says something about the facility. 2. How much WIP is sitting around on a visit? With the best vendors I've worked with you'd swear they didn't do anything until you see their shipping lanes. Low WIP and busy shipping is another positive. 3. Ask to see their rework area. If they have one and SOPs for handling rework, that is a positive 4. Ask to see their documentation for current parts. PPAP, CoC, etc.