This morning (11/2), Zillow is quoting 7.43% for 30-year fixed rates. 
CNBC reports 7.75%, Google’s aggregator shows 7.93%, the average bank rate is 8.09%, Mortgage News Daily cites 7.69%, and the Mortgage Bankers Association lists 7.86%. 
I get that minor variations can happen because of credit score, state, loan amount, and down payment, but why is Zillow so off? 
Any thoughts? 
Most likely, only one business in the area offers it. However, those terms are probably so specific that hardly anyone can take advantage of them. It’s like the car dealer advertising a $99 monthly Camry. They have one on the lot, but it’s just a teaser to get you in the door, thanks to the ridiculous conditions that make it nearly impossible to qualify.
I laughed when you mentioned the Camry. Occasionally, they “JUST sold it.”
I once had a dealer explain the price to me, attributing it to rebates I didn’t qualify for. However, there was still about $2,000 they couldn’t account for.
The “teaser rate” is a tried-and-true method for driving traffic or clicks. Similarly, some businesses hold sales for every season or holiday, which are essentially the same sale but still attract customers. Both tactics are effective but can be misleading, in my opinion.