It does often (but not always) show up well in searches but I think useablilty is partly an issue.
I find it odd the way the site shows some info and then in a different spot shows more.
For example if I navigate in to my region of the state
http://www.lanierbb.com/New_York/_Finger_Lakes/
and then scroll down to a large city, lets say Syracuse (the list looks like there is a large selection as I am scrolling so I would think it is a list of ALL the B&B's. ) Then I get to Syracuse and see only one B&B listed (Syracuse is a fairly large city...why only one B&B???) That would leave me thinking either that there are not a lot of B&B's in this city, or this site is not a good resource. Only if I am smart enough to click on the link to the actual syracuse page, do I get to see that there are 5B&B's for the city
http://www.lanierbb.com/syracuse-new-york-bed-breakfast.html (they are pulled in from nearby regions, but that's not clear either).
What I do like is the compare feature (similar to a lot of shopping sites) I think that part is great.
It's not a horrible directory, there are worse, that do better. I think one thing it does suffer from despite showing up well in the search engine results is the address. It does not give the impression that it is a directory, it looks like a single inn so when it shows up in search results and you are scanning for what seems like the best pick, are you going to pick something with an address like bbonline.com, bedandbreakfast.com or lanierbb.com ? Lanier is a pronoun so it sounds specific, like the name of a single inn, not a directory of inns.