I have 2 orders and got some opt ins but no sales. Do sellers use PTC? No offense but something is not right..
It depends from vendor to vendor, imagine buying 50$ in FB ads, does that guarantee any sales? Solos are no different :) Its just advertisement, not a guaranteed money machine.
I ordered solo ads twice and had some opt ins but I do not have access to program's autoresponder. Then I checked the emails at backoffice and found out some of them do not exit. Fake email addresses. My mistake on that part. So now I have my own autoresponder so future opt ins have to click their email addresses to get more info so that way I will know that their email addresses do exit. Will try solo ad when I have enough funds.