(Apparently, so I’ve heard) there are more sits than there are sitters (in the UK, U.S, Canada & Australia) so sitters have a lot of choice and competition between listings is high if you are in one of these countries. As @Garfield said, you can add you listing for feedback - here’s how: How to add a listing or profile link to your FORUM profile
You can also have a read of this blog to make sure your listing is on track:
As for sitter response, invites have a very low success rate due to inaccurate calendars (they are basically useless for sitters as they cannot enter their personal availability) and most sitters are not interested in sitting in their own local area. Many sitters may also withdraw their application or may no longer be available for your sit dates if there is no response from a HO within about 3 days or so, so make sure your responses are timely (if they aren’t already).
As for sitters showing up late or flaking - sorry this has happened to you, it must be very frustrating.
Hope that helps!