In their results file people often find lines like the following:
800 hits after first visit for '50000:350000[SLEN] '
The term 'first visit' relates to a stage in a typical PubCrawler
run, where numerical id's of
all reports matching a given
search query are retrieved from PubMed or GenBank. These will then
be compared with the local database and only for the ones that haven't
been seen before, a full report is requested during a
second visit
to NCBI.
There are
more details available about how PubCrawler works.