My question is does a person acknowledging that they understand the
rights impact anything or do they simply need to read them?
What if the arrestee responds with "Sorry I'm too drunk to understand
that right now", what if they just lie and say "I don't understand
them sorry". Would that be the same as not having been read your
rights?
Acknowledgment is not required and (at least in practice) neither is understanding at the time, although adequate communication for the suspect to hear them (e.g. not relying on oral warning to someone who is totally deaf, or an oral warning made while someone is unconscious) is necessary for reading someone their rights to be effective.
Of course, acknowledgement is one way to confirm that someone heard their rights, so it certainly doesn't hurt for a police officer who wants a confession to come in to ask for and receive an acknowledgement as a "best practice," when it is possible to do so.
I acknowledge the authority cited by Jen in her legally well supported answer about the requirement that a "waiver is made voluntarily, knowingly and intelligently" in light to the "totality of the circumstances" which "reveals both an uncoerced choice and the requisite level of comprehension" from Moran v. Burbine, 475 U.S. 412 (1986). This remains a correct statement of the black letter rule of law in most circumstances (as the question notes, there are always some minor exceptions to almost every rule of law).
But this seemingly daunting legal test, in practice, is applied leniently when law enforcement has gone through the motions of formally delivering a Miranda warning if law enforcement has not continued to question a suspect who has made an unequivocal request for an attorney.
While the legal standard sounds demanding, the fact patterns where courts have allowed a confession to be admitted into evidence belie this seemingly high threshold for waiving the right against self-incrimination.
Convictions obtained, in part, based on post-Miranda warning confessions where the defendant's comprehension of the warning is subject to reasonable doubt, are regularly upheld, either with a boilerplate finding by the court that the confession was voluntary, despite suggestive evidence to the contrary, or based upon the theory that admission of the confession was harmless error. The case of United States v. Turner, 157 F.3d 552, 555 (8th Cir. 1998) which Jen cites, is a good example of this leniency in practice.
Of course, it also bears noting that Turner was decided in the 8th Circuit, which is the third most conservative of the 13 federal appellate court circuits in the U.S. (including the 1st to 11th, the D.C., and the Federal Circuits) with the 11th Circuit being the most conservative, and the 5th Circuit being the second most conservative. Conservative judges tend to be extremely reluctant to throw out a confession on the grounds that a waiver wasn't voluntary, while liberal judges are still reluctant to do so, but do so more often.
A basic fact to keep in mind is that a significant share of people who commit crimes and are arrested for doing so are really stupid people who are impulsive, have bad judgment, and are prone to making bad decisions, even when they are stone cold sober. And, most of the time, they are also drunk and/or on drugs. This stupidity, poor judgment, and intoxication is why they committed the crimes in the first place. And, this is why they confessed to it once they were arrested, even though the police didn't actually have a strong case against them before they confessed.
Basically, judges (a plurality of whom were former prosecuting attorneys themselves) are loath to acquit someone who confessed to committing a crime or incriminated themselves after being read their Miranda rights who didn't ask for an attorney. Subjectively, these judges believe that there is a very high probability that someone doing so is guilty. And, judges who allow criminals to be convicted, based upon confessions made by people who didn't really fully comprehend their rights, rarely receive any negative political or professional consequences for doing so. They are also influenced subconsciously by the fact that being stupid or under the influence is only extremely rarely a defense to the substance of the crime itself, which influences their sense about when someone is mentally responsible in general.
Indeed, the empirical evidence from wrongful conviction cases suggests that judges and prosecutors probably greatly underestimate the frequency with which false confessions – especially from people who (invisibly) are actually very mentally weak – are made by suspects.
Does this reality make sense in terms of what is fair?
Yes.
While it wasn't true initially, six decades after Miranda the reading of rights is basically a talisman or symbolic cue rather than an attempt to communicate an idea for the first time anyway. It ceremonially clarifies for someone that they are under arrest, and it reminds them that they have rights that they already knew about.
It is in the same category as the administration of an oath to a witness which really is just a symbolic cue that you are supposed to tell the truth and might get in trouble if you don't. The words of the oath taken by a witness aren't even really literally true. Your job as a witness is to answer the questions that you are asked, not to tell "the whole truth."
I doubt that even 5% of U.S. born people and people raised in the U.S. since childhood have not heard Miranda rights recited many times in fiction and non-fiction media. Likewise, almost everyone knows perfectly well that they have a right to remain silent and that anything that they say after that is recited can and will be used against them in a court of law, when they are arrested and someone reads them their Miranda rights even if they are too addled to follow what is being said clearly in the moment. U.S. police procedural fiction is so popular worldwide that probably a majority of adults in the entire world know these things.
The seriously drunk person hearing their Miranda rights recited by a cop isn't trying to figure out what those words mean. They are, instead, receiving an auditory alarm: "dude, you've just been arrested" and a reminder that "you can shut up and say nothing." These are both facts and concepts that the drunk person already knew and absorbed when they were sober, probably many years earlier.
Another similar area of law is that when you sign a written contract, you are bound by all of its terms, whether or not you actually read it, subject to only narrow exceptions.
Can you be forced to acknowledge that you have been read the rights?
No.
You have the right to remain silent.
