There are many bid-bots listed on the https://steembottracker.com/ website.

A word to the wise though: Not all bid-bots listed there give a positive ROI, some are regulated to always serving a negative ROI.

When I look at the bid value / vote value ratio of the bots some do not have a bid value/vote value ratio that is positive. Some in fact you can't bid on without loosing money and some are a gamble if more then 2 people bid on them.

I collected the bots that have the worst bid value / vote value and placed them below.

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Let's look @kittybot first

@kittybot has a minimum bid value of 0.05 as circled in red above, but the vote value for the 0.05 bid is a 0.02 vote, circled in purple. If you bid on this bot you loose 4/5 of your USD value.
0.02*0.75=0.015
0.015/2=0.0075 SBD
0.0075/4= 0.002 STEEM

YIKES!!

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Next let's look at @discordia:

The vote value is 4.8X the bid value, that looks profitable... let's check some math....

If 2 people vote min bid votes (0.1)
0.24*0.75=0.18
0.18/2=0.09
0.09/4=0.025

We would loose SBD here but gain a little SP ... With only 2 voters ...

If 3 people vote with min bid (0.1)
0.16*0.75=0.12
0.12/2=0.06
0.06/4=0.015
Loss of both SBD and STEEM for all bidders

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Finally @estream.studios

Let's use 2 minimum 0.5 votes:

1.25*0.75=0.9375
0.9375/2=0.46875 SBD
0.46875/4=0.117 STEEM
This would be a SBD loss but a slight profit in terms of USD. If anyone else bids on this auction after our 2 bids, all of the will be a loss.
A 0.2 bid would be more appropriate for this bot.

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When gambling at any vote selling auctions I suggest you skip over any auction where the vote value isn't at least 10 times the bid value. As we can see above at 5X only 2 bidders can bid on @discordia before the auction become unprofitable. Please check your math before you vote.