Playing a rubbish opening is a legit strategy. Personally, I like it when my opponent tries that, as it means the opponent is not playing best moves. You should have a better chance to win. If you lose your cool because you he made you uncomfortable with unfamiliar moves, then you are playing right into his hands. Stay calm and look at it as an opportunity.
Arrogant people.
I've not a lot to do at the moment, so thought I'd chip in.... The OP is, in my extremely humble opinion - talking utter shite. There we go....that cleared that one up. You are most welcome.... David

And the spellchecker that wants to change practise into practice was programmed by someone who doesn't understand English grammar; but am I complaining?
That's probably because chess.com is an American website and so uses an American English spellchecker.
The difference between practice and practise mainly comes down to British vs. American spelling. In British English, practise is a verb and practice is a noun. In American English, practice is both the noun and verb form.

You are right when you say that sometimes, emotions or "bad" intentions can be detected in the way the oponent plays.
Are you sure this is true, and not just in your mind?

@Optimissed sometimes you have to know a concrete line of a dubious opening, not just the «first principles», otherwise you are toasted

@IpswichMatt - you're totally right, British English is proper English. Howgh! I hope it sounds arrogant enough

You may discover:
the serenity to accept the things you cannot change; courage to change the things you can; and wisdom to know the difference.
@PawnstormPossie - I feel miserable because of my lack of wisdom, not only in chess
Sometimes, a miserable failure is constantly trying to improve. There is a wisdom in that type of thinking also.
In the long run, the key to victory is the ability to go from failure to failure without loss of enthusiasm.

Chess players are supposed to be Arrogant! Ask Fischer. Ask Kasparov.
@bong711 - I hadn't a chance to ask Bobby Fischer about chess because I didn't play chess neither in 1972 nor in 1992. Asked Garry Kasparov for 2 blitz games in 1997. He beat me twice! Didn't ask Magnus Carlsen, yet

@IpswichMatt - you're totally right, British English is proper English. Howgh! I hope it sounds arrogant enough
Hey I was only pointing out that optimissed was correct for uk but that the spell checker was correct for USA. I’m not claiming British English is better or anything.

Chess players are supposed to be Arrogant! Ask Fischer. Ask Kasparov.
@bong711 - I hadn't a chance to ask Bobby Fischer about chess because I didn't play chess neither in 1972 nor in 1992. Asked Garry Kasparov for 2 blitz games in 1997. He beat me twice! Didn't ask Magnus Carlsen, yet
Wow you played Kasparov? What was he like?

@IpswichMatt - I think legendary English GM Anthony Miles described perfectly how playing against Gary Kasparov looks like after their 1986 match in Basel. Following this encounter, Miles commented: "I thought I was playing the world champion, not a monster with a thousand eyes who sees everything". Miles drew only 1 game and lost all 5 rest. Kasparov won the match 5.5 - 0.5 (+5-0=1)

Amongst Kasparov's most impressive feats were his clock simuls against 4 GMs in 1998. Seems unbelievable
https://www.reddit.com/r/chess/comments/a7rtd2/in_1998_kasparov_played_a_clock_simul_under/
In all cases is the emotion that it produces in you, that seemed to cause your discomfort.
You are right when you say that sometimes, emotions or "bad" intentions can be detected in the way the oponent plays.