People who make generalizing statements about how sex works (’if i do this my partners always always…’, ‘I can make anyone…’, ‘all men feel this thing’) either:

• Have never dated and fucked an incredibly monotome bunch of very similar partners, in most cases all cisgender, abled, etc. and consider their own experiences to be universal. 
• Have never made anyone feel comfortable enough to tell them what they’re really feeling.
• Are lying to try to sound like they know what they’re doing.  

Or all three of the above. Whichever thing is true, they’re bad news. 

So generalizing statements about how sex works are a very good warning sign that I probably should not have sex with that person.