I've never met a Polish person I feel like I could actually trust. They always seem to be a warm or nice bunch of people but to me this all seems feigned.
I've had completely the opposite experience. In general Polish people are honest, sometimes even bluntly so. American and British people act 'warm' and 'friendly' and then stab you in the back.
they always seem to act like a clan. If you don't agree with a Polish person, then they will tell the other person etc. and you will be booted or ostracized from their social group.
A lot of people act like - it isn't a Polish trait. Plus there are also many who don't act like this - stop generalising.
Maybe it seems kind of rude of me to ask but I have actually never met such people with such a seemingly deactivating negative or arrogant atmosphere as the Polish... And also a love/hate relationship.
Personally I think you're just here to provoke. Polish people are not known for being negative or arrogant. You just posted this to get a reaction.
Poles are very jealous people and they would actually rather want to see the other Polish person fall into the mud rather than be more successful than themselves.
This is the only accusations you have made that has some truth to it. Polish people have been known to resent each others achievements and tell on each other, particularly in foreign countries. People of other nationalities generally stick together more.
There was an interesting story told recently, by somebody who did an interview with the immigration office in the USA and asked why so many Polish people were being deported from the USA, but for example, not many Mexicans. He asked if the crime rates etc. were that much worse with Polish people? The person he was interviewing laughed and said 'no, the difference is, when a Mexican is here illegally, his fellow Mexicans hide him and help him out. When a Polish person is here illegally, his fellow Poles, rather than keeping it quiet and helping him out, decide to hand him in. This is why so many Poles get caught and handed in.