Things change and yet remain the same. Backpage is kinda the new streets. Although backpage does normally charge for ads, they had some trouble with Visa and so for awhile had some sort of two-tier system where I think some of the girls could throw up an ad for not much money. (don't know BP from the advertising side - maybe someone can add info?)
So much the same as the old days there are real ads, shill adds and some flakey/spam/conning ads (ones that want you to sign up for an 'ID Verification' screening service, for instance). There are some that promise everything for not much (eg: Suzanne @ the Norwood) and you DON'T want to experience(!) and one that starts posting once in awhile (? on Idylwyld/Ave B) - she has some adds with her picture that seem kinda normal, but check the 'Also' ads from her account and you will see flat-out stolen pictures and random, rambling word-jumbled ads that are kinda scary (or a really bad joke?)
Probably best to watch awhile, see which ads come and go, and use your judgement - if they offer $100 'specials', open 24-7, multiple girls same number, probably best to use caution.
Good luck!