I started to post something similar but stopped, thinking maybe it had some non-derogatory meaning I wasn't aware of. Maybe some people use it interchangeably with 'rug rat', 'crumb snatcher', 'ankle biter', 'curtain swinger', and other semi-affectionate nicknames for children. I've never heard 'porch monkey' used in any way other than as an insult, and primarily as a racist one.