Please don't misguide people for unknown reasons. Primary maintenance of this train is at Kamakhya and you cannot hold SWR responsible for this. Chips, tea cups might actually be thown by people who have boarded the train and it is the responsibility of the on board maintenance staff which is actually NFR and not SWR (Passengers are also equally responsible). Cockroaches doesn't appear suddenly at YPR but is there due to improper Primary maintenance.
Also, the traveller has posted Entry# 1329356, which clearly shows the negligence at Primary Maint.