There are both ethical and unethical side of using bid bots. It depends on users how they will use it.

Let's talk about unethical side first.

You will see there are some users on this platform sharing very low quality content which doesn't add any value to the platform. But still they have plenty of rewards in there posts. They are just using bid-bots on their post. It can be said that, they are stealing from reward pool as they are adding nothing to the platform but getting many.

Let's talk about ethical side now.

Bid-bots are brought in place of promote. You can see a promote option below of your post. By sending sbd you can promote your post. But this promotion doesn't ever cover half of the spend money. Then bid-bots came and now a good content creator can boost his post through bid-bots and it gets more influence than that promotion option.

Without these bid-bots also have blacklist and whitelist. The user who continuously share low quality content and keep using bid-bots on them, get blacklisted by the bot owner.And this system is getting more optimized day by day.

In this world everything has a good and a bad side. You can cut fruits by a knife and can also kill a people with it. It will depend on you, how you will use it.