Wow old thread. Meh, I'll give my opinion anyway.
The OP talks about "saying things to the opponent". I think that's thin ice. Complimenting on a good shot is good sportsmanship imo.
Talking thrash is a big no-no.
I most definitely use mental games / tricks during play. Always. Even when I'm winning hard. But most aren't as much geared to annoy my opponent as they are to uplift myself.
Like one thing I always do when the opponent is serving... Say it's 40-30 and there's a ball on my court that requires clearing before the next point. I will send it over to the other side even (or especially) if the opponent already has two balls ready to start the next point. As if to say "
you will need more balls for more serves after this point, because the game won't be over". Conversely, in the same situation but at 30-40 breakpoint, I'll put the ball in my pocket. As if to say: "
I'll be serving next point anyway...."
I do this primarily for myself to put myself in some type of "confident" state of mind. But attentive opponents do pick up on it and it might get inside their heads.
Another thing I dare to do, is to break the opponents rhythm. Say he's serving super well and is in a great flow. Right before next point starts, just before he's in position to serve, I might drop down and retie my shoelace. Just to "break" the rhythm. I would never do that if he's already in position to serve though, I consider that bad sportsmanship. And most certainly not between first and second serve. But if he's not yet in position (say he has another 3-4 steps before being in place) - sure, I might.
And he'll have to wait 5-10 seconds to start serving. On a psychological level, that puts me in control of the flow of the point. It's also for myself - clear my head, take some seconds to catch my breath, etc.
All these little things are part of the game. Tennis is very much a mind game in a very real way.
No, it's not cheating. By definition, only things that are counter the actual rules, is cheating.
To me it's more a question of good or bad sportsmanship. There are things that have a fine line though.... Like the retie the shoelace thing....
You might call it bad sportsmanship... To me it all depends on when you do it.
If the guy is already in position to serve and is actually starting to bounce the ball and you then say "stop" and drop down to unnecessarily tie your shoelace... = bad sportsmanship.
If the guy however is NOT in position and still walking from picking up balls and you do it then = ok. Not "good sportsmanship", but not bad either. Just neutral. His serve rhythm hasn't start yet and we are in between points. It's fine.
It becomes bad sportsmanship again if you do it multiple times per game or set.
Having said all this.... none of this will actually make you "win" or "lose" matches imo.
At best, it might help you win an additional point left and right. Might be crucial points, yes.... But a match consists of 60 to 100 points. More if the match is tight.
I can't imagine walking away from a match thinking "
If only he didn't retie his shoelace at 30-40 in the second set, I so would have won that match".
Sounds pretty bonkers to me.