This isn't to invalidate your point completely, but to give some insight to those who are not aware of how this conflict of interest has been generally handled.
The case of Donald Trump is a perfect example. He had conflicts of interest galore, didn't even deny them, in fact he flouted them, and many people seemed to think everything was fine.
We need to be aware not only of the existence of conflicts of interest, but also of (1) how corrosive these conflicts are, and (2) the crucial importance of designing systems to minimize the bad incentives and effects that arise from conflicts of interest. Systems, in other words, that minimize the harm that -- because of human nature -- inevitably flows even from well-intentioned people when conflicts of interest are tolerated.
Yes, you really need to ask that. When accusing someone of misconduct you really do need to ask if it is really happening and not just hand wave about human nature and make judgements based on untested assumptions. You really really can’t just go along with whatever fits your biases.
On the other hand, regardless of intent, it does still make sense to say that the system is maladjusted, that the system is designed in such a way that even actors with good intentions are incentivized to do harmful things. And the question regarding the system really is clear: Does a recipient accepting money from an advertiser tend to create in them a more positive opinion regarding the advertiser than if the recipient received no money at all? To that, the answer is yes. It doesn't mean the recipient has committed "misconduct"; more likely it's just that the recipient is a well-intentioned actor in a maladjusted system.
If a person does something wrong but is not aware that what they did is wrong, the general reaction is not to "accuse them of misconduct", but rather to explain to them what it is about their action that's wrong, after which (if they in fact have good intent) they will no longer do that action.
It's also worth noting that quite a lot of broad crimes are strict liability these days, especially in America. For example money laundering is a strict liability crime, along with more obvious ones like speeding.
Misconduct though is not normally a criminal law term anyway. More like a code of conduct for an organisation.
Jimmy Carter put his struggling peanut farm in a blind trust to avoid the appearance of corruption. This has become a punchline today, but was standard at the time.
Frankly, the corruption of the Clintons, who generally took turns raking in cash while the other performed duties as a public servant, sent the dominos crashing here.
Because corruption is incredibly easy to hide and obscure, it is correct to cultivate a culture of transparency accountability when, for example, tens of millions of dollars change hands between powerful institutions for no apparent reason.
My question is: Do you really need to ask that? Human nature is human nature; there's little doubt that it's happening to some extent. Virtually impossible that it's not happening at all.
The problem to me seems quite similar to campaign contributions in politics. Yes, it's indirect, and all parties can say it's innocent, no strings attached, the elected representative is not "required" to do anything. Those are words that help people ignore the reality of human nature. Money is influence.