How do I evaluate an unlimited bandwidth residential IP provider?
Read the pricing page for the word that qualifies the promise. Unlimited with a fair-use clause that throttles above a threshold is a data cap with extra steps; unlimited on a plan whose base price scales with a bandwidth tier is metering by another name. What you want is a price attached to the proxy count and nothing else, which is what per-IP pricing means here: $0.60 per static residential ISP proxy, $0.32 per datacenter proxy, no data component in the calculation.
Second thing to check is whether the residential IPs are dedicated. Unlimited traffic on an IP shared with strangers is a weaker offer than it looks, because their usage shapes how your IP is treated by targets.