A few days ago I got asked the following question by 
“Just working my way through the witness list at steemian.info and have one question,
. Do you, as a witness, support vote bots?”
Well, the short answer is Yes but I would like to expand on that answer and also differentiate types of bots and what they bring to the table.
Upvote Bots
In the early days of Steem we struggled to find value in Vested Steem (Steem Power), there was no real reason to hold except the small benefits you could obtain from curation and by voting for yourself, which is probably in the same moral ground as buying votes.
The whole phenomenon of vote buying has added a steady demand for Steem that comes from dolphins and whales who seek profit by locking away their Steem and selling their votes.
In this sense, vote buying has Direct Market Impact by adding demand and shortening the supply of Steem. There is no doubt in my mind that banning or prohibiting vote bots will generate a massive sell-off in the market.
But there is also other benefits of vote bots, in one hand you have the marketing aspect. Buying votes provides exposure to unseen posts, all platforms like instagram, twitter or Facebook offer similar services, where your posts can be ranked higher if you pay those companies, difference is that in Steem you are paying other token holders, is a new form of Decentralized Marketing.
The other aspect that has really kicked in is the Gamification of vote-buying. We now find people playing with bots, finding the best time to put in their bids, sending SBD to different bots, making excel sheets of the possible returns, etc. Just by looking at the active user base of 
Comment bots and Social Mining
We also have another set of bots that I would like to call Social Mining Bots. This bots pretend to obtain part of the reward pool by sending automated messages to the Blockchain.
To illustrate how easy and fast you can create one of these bots, I took 2 minutes of my time to write this code:
import random
first = ["this", "the", “your"]
second =["photo", "picture", "pic", "shot", “snapshot"]
third = ["is", "looks", "feels", "is really”]
fourth = ["great", "super", "good", "very good", "good", "wow","WOW", "cool", "GREAT","magnificent", "magical","very cool", "stylish", "beautiful", "so beautiful","so stylish", "so professional", "lovely", "so lovely", "very lovely", "glorious","so glorious", "very glorious", "adorable", "excellent", “amazing"]
fifth = [".", "..", "...", "!", "!!", "!!!"]
print (random.choice(first) + " " + random.choice(second) + " " + random.choice(third) + " " + random.choice(fourth) + random.choice(fifth))
If you add the outcome of this python script to all comments under the photography tag you would get a large combination of spammy comments:
the snapshot is really beautiful.
This picture is really magnificent..
the picture is really so stylish.
Now, I am not in the “right and wrong” business, Instagram is invaded with these photography bots and nobody complains about it. What I can say is that they certainly don’t add any value to the platform. Don’t get me wrong, I am not saying that we should prohibit or ban these bots, I am a true believer of maximum freedom, if you don’t like these comments on your posts, just flag them, I certainly do.
Utility Bots
Utility Bots are those that provide some value to the users. For example, the anti-spam bots, the twitter reader bot, a price poster bot, and so on.
These bots I not only support but I enjoy building. They are in the eyes of many the “good bots”, even tho they are also doing their fair share of social mining and taking part of the reward pool, which is ok, people who build cool stuff should be rewarded for it.