Not only do I doubt that Scranton has the worst drug problems in the country, I know for a fact that it does not have the worst drug problems in the state.
As a former resident of eastern PA, I would have said that Reading, which has a smaller metro population, has far more drug-related crime. Sure enough, I was right; see:
And search for YTD crime data for 2001.
The Scranton-Wilkes-Barre-Hazleton area, with about 650K population, had 1167 arrests for drug offenses of all types in 2001
Reading, with about 310K metro population, had 1431.
The uniform crime statistics do not break out the percentage of violent crimes that are drug-related, but based on the above I’d be extremely skeptical of the claim made by the police officer mentioned in the OP.