For us, "SEO" has a strict definition - optimising sites for ranking in search engines. For site owners, SEO means more visits/sales/conversions. If the visits are referrals from well-ranking Local sites (sites that rank for location terms), they don't mind.
So I took a look at TripAdvisor and used its internal search for "<placename> motels" for a small town in NSW that has about 20-30 motels.
TA has over a thousand results for it. The default results are not ranked by:
- Star rating - the first result has four stars, then some five stars, a three star and so on.
- Recency of reviews - the listings were from the last three years.
- Number of reviews
I tried a Google search for the TA domain and the same query. Most of the first 10 results are generic pages and only two specific motels, neither of which were in the TA search result.
The TA page code does not validate, but shows some minor signs of SEO. Extensive atructured data tags exist in the form of rdfa, which helps with location based queries.
I didn't check the number of backlinks to individual TA results.
The only conclusion so far is that TA and Google have different ranking algos, so if you don't rank in one, you might in the other. :)