Introduction
When you submit a genome assembly, or NCBI assembles the reads you submitted, it ends up in Genbank. If the assembly is of sufficient quality, it is annotated with PGAP and added to Refseq. Note that this means the same assembly can exist in Genbank (with your original annotation) and in Refseq with the PGAP annotation and a different accession number.
There are many reasons why a Genbank assembly could be denied admission to Refseq, and here I outline how to find out if the genome you are working with is potentially bad, and why.
Commands
wget https://ftp.ncbi.nlm.nih.gov/genomes/genbank/assembly_summary_genbank.txt
pip3 install csvkit
csvcut -t -K 1 -c 'excluded_from_refseq' assembly_summary_genbank.txt \
| tail -n +2 | tr ";" "\n" \
| sed -e 's/^ //' -e 's/ $//' | grep -v '""' \
| sort | uniq -c | sort -nr
Results
198215 derived from surveillance project
32538 derived from metagenome
16820 derived from environmental source
10389 metagenome
4684 low contig N50
2187 partial
1822 many frameshifted proteins
1568 derived from single cell
856 genome length too large
820 genome length too small
752 high contig L50
562 low quality sequence
357 contaminated
352 missing tRNA genes
309 abnormal gene to sequence ratio
274 validation errors
194 missing ribosomal protein genes
114 missing rRNA genes
104 untrustworthy as type
77 unverified source organism
38 misassembled
12 mixed culture
6 chimeric
4 low gene count
2 hybrid
Conclusion
Stick to using genomes from Refseq wherever possible. The main exception may be if you are working in public health microbiology, then the "derived from surveillance project" reason probably means it is part of GenomeTrakr and might still be of importance.