I tried using the bid bots to get some visibility on my post because i believe i have something important to say. However, the bid bots neither gave me visibility or my hard earned SBD. I stopped using them immediately. Instead I use bots like @thehumanbot who actually reads your post before it promotes it. After that, I wait for curators to naturally come across my post. After that, then I invest in fixed fee bots like minnowbooster. They only give small SBD over you initial investments but you don't make a loss or loose your hard earned SBD.