Nasty Dolls has improved somewhat, but the recent problems have been:
1) The girls listed on their site are hardly available.
2) They will offer girls that aren't on their site.
3) Poor email and/or telephone response.
The girls aren't bad, it's the management that is slacking when it comes to dealing with customers and having available girls. If you can confirm an appointment, it generally won't be cancelled.
There is no absolute certainy in this business, but if you still with one of the groups we cover, you should be OK.