1. Verify the business license — and what it covers
A real manufacturer's license lists "electronic products manufacturing" (电子产品的生产与销售). A trading company's says "trade" or "import & export". Ask for the unified social credit code and check it on the public registry. If the scope stops at trading, the "factory" you are chatting with is a middleman adding 15–30% to your quote.
2. Ask for the factory address — then video-call unannounced
Trading companies share Shenzhen office towers; factories can put you on a live video walk through the floor. Ask to see the SMT line and the assembly line for your product category during the call. Ten minutes of live video beats ten pages of a glossy deck.
3. Ask which certifications the FACTORY holds, not the product
ISO 9001 is a floor, not a ceiling. For kids' electronics you also want in-house testing for CPC/ASTM F963 (US) and CE/EN71 (EU) — ask which tests run in-house versus outsourced, and how often. A factory that runs high/low-temp, drop and transport-vibration tests in house will ship more predictable mass production.
4. Make the MOQ question specific
"What's your MOQ?" gets a marketing answer. "What is the MOQ for a custom shell color with my logo?" gets a real one. Many lines quote a low MOQ for stock colors and a much higher one for tooling-level customization — get both numbers in writing before you design anything.
5. Get the compliance pack scoped for YOUR market
A proper quote itemizes the test reports for your destination market: CPC for the US, CE/EN71 plus RoHS for the EU, and CPSIA tracking labels if you sell into retail programs. If a supplier waves this away with "we have CE", push back — ask which lab, which standard version, and whether reports carry your product's photos.
6. Ask what happens after shipment
Real manufacturers answer for the batch: warranty terms, defect-rate commitments, and spare-part or firmware support for app-connected lines. If the only after-sales answer is "contact the app company", you are talking to an assembler, not a partner.
7. Test responsiveness with one small technical question
Ask something specific — shell wall thickness, battery certification, a UI language list. Manufacturers answer in hours with engineering detail. Trading companies answer in days with "let me check". You are about to send this team your designs; their default speed and precision is your future.