It honestly depends. Eros is a lot of money, and in some cases, doesn't produces great returns unless you shell out MORE money. If you're including the base-price of the ad, plus add-ons, it can total a lot more than the cost of a session for sure. I think your advice about raising rates is solid advice, and from the description you gave, it seems to fit. If the market is higher density (like New York, Chicago, or LA), you have to dish out the dime to even get your ad seen unless you've got "available now" on all the time.
If she's really only semi-UTR, she may want to consider experimenting with a free website as well. With that price, certain levels of social media are expected, and a website also makes her
VIP might garner more hits, but things like authenticated photos automatically add you into other categories, and it doesn't cost more to add that to your ad.
You may want to try Slixa as well. It seems to be far more popular in SF and California in general than it is elsewhere. Other verification service websites like P411 and Date-Check are also viable options instead of Eros as well, but she has to be vouched for in order to become a provider member of those sites.
Bottome line- the more diverse her advertising strategy, the more clients she'll get. If her ad copy is correct, that alone will help filter out unwanted business and further attract the types of clients she's really after.