No one, left or right, thinks there is street level corruption. Not the kind accessible to someone in a traffic stop. I have experienced it in Mexico and think that kind of corruption would still be worse because I cannot imagine how to recover from it. I have hope that a few high profile arrests of c level fall his may turn the tide. If not then there are extrajudicial methods open to American culture.
I know from my own personal experience that I haven't paid a bribe to a cop or to an alderman to get a zoning variance. There are some places where this kind of thing is routine. (e.g. I know there is a crooked cop somewhere but I also believe that if I tried to pay a bribe to a cop it wouldn't go well)
Thus I trust people's reports of street level corruption.
If it comes to perceptions of "corruption in high places" that is mediated by the media. It may well be that it is very corrupt and you never hear about it, or that it squeaky clean but you hear allegations 10 times a day. Or a Democrat might think everything is corrupt when Republicans are in power and then when Democrats are in power, Republicans take up the slack.
So I don't trust people's reports of corruption in high places.
Now I know a lot of people who are involved in road construction and maintenance in upstate NY who range from "drives a truck" to "manages $10M+ projects" and the belief that there is corruption in highway projects is widespread based on second- and third- hand accounts.
Totally unthinkable in the UK ( at least outside organised crime ).