On the kindle, if you reposition yourself back to page 1 of a book, those dots go away. SOOO you can't alway tell.
PS Maybe I'm too old school -- again, I use my off-kindle list (or a different list) to keep track of what I HAVE read, and what date. Just cause I like to know. Occasionally I search for when I read that particular book. For instance, I just realized that I read a whole dozen Pratchett books just last year. I'm catching up on his stuff too fast; gonna run out! I thought I was saving them up and savoring them. I guess I can always start over. )
PPS I search the Kindle Clippings file to get the date on the last few books I've read ... then I delete the clippings file. To keep it small.