Sometimes job listings use slashes and hyphens in the title of the job to specify specialties or other job characteristics. For instance, here are two listings on stack exchange: Data Scientist - Dynamic Pricing, Data Scientist/Machine Learning Expert. The first line of my cover letter is usually something like "I'm writing to apply for position X at company Y". What is the best practice for referencing the job title in this sentence? Is it acceptable to quote the job title with hyphens or should I simplify to an essential title like "data scientist"?
Do it exactly the same way the company does it.
If you know what job to apply for, it's because you saw it in an ad, on their website, or in another listing.
The hyphen and the slash are used differently.
The hyphen means "this job is for a data scientist doing dynamic pricing."
The slash means "this job is a combination data scientist and machine learning expert."
It can be subtle and it may even be that many jobs can use either. But they have that punctuation for a reason (probably), so keep it.
Don't shorten it.
Don't just say "data scientist" because they'll wonder which of the many data scientist jobs you meant.