What is a word/expression for useless advice?

There is a business concept of 'true but useless', more commonly applied to information rather than advice, but it may capture some of what you are looking for. The phrase 'technically correct' also conveys the same idea (the inclusion of 'technically' means that 'useless' can be left out and would be understood).

From here:

I have sat in too many meetings where people have established facts which everyone in the room agrees with. The problem is often that these facts are completely irrelevant to any action that can be taken. “If we had more time we could do this” is said when no time is available. If you can’t do anything about something why focus on it?

It also calls to mind this old joke:

A helicopter with a pilot and a single passenger was flying around above Seattle when a malfunction disabled all of the aircraft's navigation and communications equipment. Due to the darkness and haze, the pilot could not determine the helicopter's position and course to get back to the airport.

The pilot saw a tall building with lights on and flew toward it, the pilot had the passenger draw a handwritten sign reading, "WHERE AM I?", and hold it up for the building's occupants to see.

People in the building quickly responded to the aircraft, drew a large sign, and held it in a building window. Their sign said, "YOU ARE IN A HELICOPTER."

The pilot smiled, waved, looked at his map, determined the course to steer to SEATAC airport, and landed safely. After they were on the ground, the passenger asked the pilot how the "YOU ARE IN A HELICOPTER" sign helped determine their position.

The pilot responded, "I knew that had to be the Microsoft support building, they gave me a technically correct but entirely useless answer."

You could get close to your sentiment by thanking Captain Obvious. The emphasis is less on how useless the information is and more on how self-evident, but there's often overlap. Your example of "Well if you didn't get a loan in the first place, you wouldn't be in this situation today..." could easily be replied to with a nice sarcastic "Thank you, Captain Obvious". If he's not around, you could go with Captain Hindsight instead, for when the advice is only obvious now and might not have been in the past. Either way, it's technically correct but useless advice, so could work for your scenario.

"It's not worth the paper it's written on."

When a suggestion or advice is useless or not important, even in a case where it's not actually on paper, you can say it's not worth the paper it's written on. This usually involves things that are true but simply not helpful or worthwhile. An example from TFD:

Oh, that memo is not worth the paper it's written on. You know the boss is going to completely change her mind about it in a few days anyway!

Definitions include useless, unimportant, insignificant.

One colloqual answer to that type of advice could be "Tell me something I don't know?".

And the equivalent to your Czech Count in popular english expressions would be "backseat driver" or "armchair coach". So the advice could be characterized as "backseat driver advice", or "armchair coach advice".

You lose the "haughty" aspect of the Czech expression, but it's the best I could come up with.