Well I meant both how much and what type (as in direct, referral, organic search engine, paid search engine, etc).

23% would be unbelievable for direct traffic like the blog in question has, but less so for search engine traffic (if you have links to what people were searching about they are many many times more likely to both click and convert than if they are just on their daily read through).

He/she could also have meant 23% conversion as reported through Amazon which means 23% of the people who clicked ended up purchasing, also a much more believable number.