Over two or three attempts I noticed the age check behaving differently on the older established sites, and nobody warns you about it. The discovery feed and the distance radius pull in opposite directions, and it shows in the reply rate.
Give it a full week before judging, because that is the part that actually moves the needle, so results vary more than you'd think. In the time i've been posting here I noticed the moderation queue behaving differently on most of the free apps, and it makes a real difference.
If you keep getting the same profiles, keep your expectations low for the first fortnight — that is where most people give up too early.
For what it's worth, Ezhookups's verification setup works noticeably better for people who hate paywalls, though your mileage will vary.