Eyewitness Testimony
These two young men aren't the two young men in question, but he's not wrong about two young men doing drugs in that room.But the rest of the family was content to act like "He has Alzheimer's and he's just whackadoodle. Ignore it."
That especially aggravated me because my mother was blind in one eye. No one just dismissed her out of hand entirely even though her handicap once resulted in her totalling a car.
Almost no one has perfect eyesight or perfect hearing and absolutely no one is always paying attention to the right details for a specific purpose. We all get through life by using partial information, proxies and pattern matching.
Additional writing by me about that fact:
Con artists and criminals intentionally use that fact to try to get stuff past people and ALL eyewitnesses are unreliable. In addition to the above issues, language barriers, cultural barriers and similar can foster misunderstandings when trying to take a statement or interpret an eyewitness statement.
Law and Order had an episode where a White cop says something dismissive about "Dottie" and a Hispanic cop snaps at him "Dadi" which is a nickname for some Hispanic name.
Vivian and Beverly are typically female names. In some culture, they can be male names. If you assume Vivian is a woman, most of the time that will be correct but not always. That was used in some story I read to foster suspicion of an affair.
We ALL pattern match to known patterns and it creates errors in novel situations. We make assumptions rooted in past experience based on partial information.
People whose language doesn't use Latin letters, like Korean, should still know Arabic numerals and may pattern match a Z to the number 2 as the most familiar character they personally know. This was a plot point in some police show where they had trouble finding the license plate.
If they have a particular impairment, a psychiatrist or similar may be able to help you try to filter the information to account for ways in which they are likely to make errors.
As mentioned in one of the links above, a study by Microsoft carefully avoided stigmatizing language like handicapped and asked if you have physical limitations and would appreciate accessible design.
I think about 20 percent of people identify as handicapped or disabled. Sixty percent of respondents said they would love easier-to-use AKA "accessible" design.
A lot of "convenience" items, like kitchen gadgets, are defacto accommodation for physical limitations. Eyesight issues are common but we don't really think of someone as handicapped if they only need glasses but aren't blind. The reality is they are handicapped and may miss details others can see just fine.
Color blindness is a common impairment that can be a potentially life threatening issue in certain situations -- reading a color-coded map in war or some other survival situation -- but is generally not classified as a disability.
It's mostly found in men and usually not that big a deal and this may contribute to it being glossed over. Historically, real jobs were held exclusively by men and that colors how important the world at large sees certain issues.
I'm not saying that's sexism. We also trend towards having more medical research on upper class White male diseases because people doing medical studies and gatekeeping funding for medical studies tend to be upper class White males.
Being genuinely interested in a male disease because you might get it and reluctant to ask a bunch of old White men for money to check out lady bits when you are male and swear it's legitimately a medical study and not a cover story for your perverted behavior isn't sexism per se.
Both moderately impaired people who don't want a stigmatizing label that will likely limit work opportunities and seriously handicapped people wanting to protect their status as someone legally entitled to accommodation get very testy about defining where we draw that line between "normal" and handicapped.
Reality: It's not true that there is a clear, bright line between the 80 percent of so-called normal, healthy people and the 20 percent of handicapped or disabled people.
That's called prejudice and it actively interferes with accurate assessment of truth AKA reality.
Last, keep in mind that differently abled is not just polite PC language to make disabled people feel better. The link above about Face Blindness talks about other ways people with Face Blindness identify people and movies where a blind person could identify people by voice or otherwise use their impairment as an advantage.
I've seen more than one TV show where a blind person was able to use other information to state confidently the make of a car or similar.
Footnote
The Law and Order episode may be Season 6, Episode 2 "Rebels." I cannot find the scene where Benjamin Bratt says Dadi but here is a 10 minute clip summing up the episode where the names Caridad and Dadi get used for the same character.
Prior to somehow finding the above information, I searched for something like "Dadi Hispanic nickname" and got nothing close to what I wanted. I remembered it being something like "Calidad" and I was getting something about Dadi and Hindi something.
If you don't know the culture and language, do not assume a quick search in English will find you what you need.