You sound like you read a lot of science headlines, and not a lot of publications
A scientist will come up with a result (this is all hypothetical) like 'this data shows that at an 80% confidence interval, in a man's beard is 64% more likely to have twice as many T. lyciniae bacteria per square inch than a canines fur (n=50)'
The scientist is trying to show that the bacteria is has more affinity to humans, or some other data driven point.
A retard reporter reads the abstract and writes a head line >DOGS ARE CLEANER THAN MEN WITH BEARDS, SCIENCE CONFIRMED IT.
A week later somebody repeats the study with a bigger sample size and finds the original data was wrong beacause the dogs were all washed yesterday or x or y or z
retard reporter says>SCIENCE CONTRADICTS ITSELF SAYING ALL DOGS ARE FILTHY ANIMALS. KICK A PUPPY SCIENCE SAYS ITS A-OK.
All you read are the headlines, then your pea brain goes "WHY SCIENCE LIE? WHY NO TELL ME WJAT IS TRUE? JEWWWWSS????"
All science is is extremely qualified statements backed up with data. (qualified meaning, having lots of ifs before it) As we get better at getting data we we contradict old points. 'Science' is not a monolith. There are competing theories on everything.