Ok, so eperimenting with the queries, I used the search module as a sort of query generator and as a link it returned the correct results.

However I have several RSS feeds coming in, which I wanted to exclude,

This was the query I used which should exclude results from the target categories for the RSS posts.

It is basically just asking for posts since last visit exclduing topics in categories X,Y,Z

/search?searchJSON=%7B%22date%22%3A%22lastVisit%22%2C%22type%22%3A%5B%22vBForum_Event%22%2C %22vBForum_Link%22%2C%22vBForum_Photo%22%2C%22vBForum_Text%22%2C%22vBForum_Video%22%5D%2C% 22channel%22%3A%5B%221%22%2C%222%22%2C%2236%22%2C%221443%22%2C%2238%22%2C%223%22%2C%2241%2 2%2C%2240%22%2C%2253%22%2C%22139%22%2C%2251%22%2C%2243%22%2C%2244%22%2C%2245%22%2C%22106%2 2%2C%2246%22%2C%2247%22%2C%22142%22%2C%2252%22%2C%2255%22%2C%22143%22%2C%221123%22%2C%2215 %22%2C%2216%22%2C%2217%22%2C%2218%22%2C%2222%22%2C%2219%22%2C%2220%22%2C%2221%22%2C%2223%2 2%2C%2224%22%2C%2225%22%2C%2226%22%2C%2227%22%2C%2228%22%2C%2229%22%2C%2230%22%2C%2231%22% 2C%2232%22%2C%2233%22%2C%2234%22%2C%2235%22%2C%221135%22%2C%22522%22%2C%2214%22%5D%2C%22so rt%22%3A%7B%22lastcontent%22%3A%22desc%22%7D%2C%22view%22%3A%22compact%22%2C%22exclude_typ e%22%3A%5B%22vBForum_PrivateMessage%22%5D%7D&btnSubmit

Now a part clue could be that I see email notficiations for these posts in my inbox, saying "ABCDE" who is a registered use has just posted in the categories for these RSS feeds, which they did not, so that notification is false, the RSS feeds have 3 dedicated user accounts which are Bot A,B,C registered users cannot post in those forums

I am also seeing results from posts in my excluded categories from that query.

Any help appreciated