Within my industry, I've spoken first hand with people that have engaged with Russia, specifically to set up a franchise of an existing entity within the entertainment business. They experienced systematic corruption at every level, they had officials directly ask for bribes, they had unsolicited contact from 'unaffiliated officials' requiring them to pay sums into accounts before 'things could move'. They were advised by their security details that the hotel provided was most likely under surveillance and to not engage in ANYTHING within the hotel room that could be used against them. They were also offered 'comfort girls' during their stay, which were all declined, (likely due to the advice from their security detail). Had they accepted, the expectation was that they'd have been on camera during any intimate moments. I'm lead to believe that said 'comfort girls' had been encouraged to offer rather 'niche' services to increase the embarrassment of anyone caught on film.
I'm a sensible chap for the most part and don't generally subscribe to conspiracy theories, but I believe what was told to me regarding the above. If Russia are willing and able to go to that length for something relatively minor in the grand scheme of things, what would they do over decades with a man like Trump?
There is plenty of accessible information out there about Trump's links and contact with Russia over the last 40 years. He is, in my opinion, 100% compromised.