It is ethical and unethical.
It depends on the individual. No one is outrightly against it.
An age old question and yet again, we all need answers at least here on musing :-)
Let me begin by saying that people have grown on Steemit by spending money on:
Bid-bot votes are not partial to good content. It’s a system where you pay to get votes - Quality does not factor into it. This is the primary reason that raises questions about ethics.
I joined Steemit in January 2018 and visited the trending page quite frequently in the early days. Then gradually my visits to the trending page declined, without me even noticing. The first time I actually consciously thought about why I didn't visit the trending page more, was when a guy I followed wrote a post about the low quality of trending posts. Without even realizing I had given up on the trending page.... (Although maybe things might have changed in the past few months that I have been inactive)
I think that people just don't read and listen to below average content. The truth is that most are not even reading the good content, so why would one think that they would peruse bad content much less upvote it. As of now bid-bod votes are only good for getting visibility on this platform. They are barely profitable but can give you enough boost to make a post trend (All my experience here points towards the fact that bid-bots are not profitable, at least not for the one paying for the vote)
One can clearly see that posts in the trending section are almost all bot voted (Although maybe things might have changed in the past few months that I have been inactive). Following where the upvotes came from is pretty easy on the blockchain. I have seen selfie posts on the trending section (worth hundreds of dollars) and it wouldn't have been weird if the selfie was of a particularly good quality. Somehow even a selfie and a substandard one at that can be pumped enough by bot votes to reach the trending status.
..... I will say once again that bid-bots and quality are two mutually exclusive subsets of this ecosystem. I will also recommend that I have seen several great steemians grow organically and I am pretty sure that you can do the same as well (this is the impression I got from the detailing of your question on musing)
Let me say this as a conclusion - Posts, good or bad can be pumped and made to trend and become more visible. Bid bots votes are not all that profitable in terms of dollars, on the other hand there are other (organic) ways to spend money and grow on Steemit, if you take all that money that you might spend on bid-bots and use that as prize for a few small small competitions, than this can attract users to your blog and allow you to gain new followers.
Bid-bots are a bad deal (unless you are a sponsor/owner of that bot and it is partial to you), not to mention the bad Karma that it can attracts. Trust me you can easily make a mark here on the Steem community without bots. We have a great example in guys like @nathanmars (awesome thinker and networker), @reddust (great artist), @coruscate (content creator). You can take a look at their journey on the Steem Blockchain and trust me you'll find inspiration there.
Neither. It’s a subjective matter, and you’ll get arguments and opinions from both sides.