Well, did not make a calculation yet... but I used 3 promotion bid bots for visibility who have a min and max ROI, so it doesn't matter to much. Bringing some value by spreading info on how to get some free money and a giveaway. If my ROI is minus after the post payment refferalls and giveaway, it's not a problem. I know the risks and planning to bring even more valuable airdrops when I see them. I also will make articles separated from the airdrops ones about the good upcoming projects out there and tutorials that can help investors, whitelist sellers alike to make some good profit.
Actually I am doing this daily now, being involved in some payed and not payed good groups. Will do some articles soon, let me know what will be your opinion on them when that happens. Cheers.