If you are using `latest` pricing and the latest bid (from the Wiki API) for Death rune is 190 and the latest ask is 194, a pricingOffset of -1 means the script will bid at 191 and ask at 193. The profit margin has fallen from 4 to 2, but you will capture more volume. Conversely, a pricingOffset of +1 means bidding at 189 and asking at 195.
I'd recommend a non-positive pricingOffset to try to capture more volume, this is probably the more consistent and less risky option. That said, I can see a large positive pricingOffset working for medium to low volume items if using oneHour pricing, but this isn't something I've really experimented with yet.