If you do everything correctly and use the methods in a complex, then you will never know that there are bots in the group.
Definitely not.
All I need to do is having a look at the members in that group, that's possible publicly in groups / supergroups and I can scroll a little bit back to see the members. If there is a significant number of bot accounts it's easily to detect them for experienced shitcoin analysts. If someone is not that dumb they won't be fooled.
Users who have come for a reward, as I think are worse than bots.
Why do you think that? If they receive their reward as promised there is not a single reason why invited people should be worse than fake bots. And in addition maybe some of these members are going to invest if it's not a scam shitcoin project. As a shitcoin artist (

) I woudn't think a second about inviting bots because it's not just useless, it's harmful for a project. Same as bumping services. If I see such shady marketing, my first impression is GTFO.
You cannot see it. On the contrary, shady marketing should consider the methods listed above. People who have come for money except for the constant outflow will not give anything to the project. They came exclusively for the money, so that after they were received, they would immediately exit.