I will answer to myself as I find a scientific article which, probably, clears me the question. It's "Endoscopic and histologic evaluation together with symptom assessment are required to diagnose pouchitis" https://www.gastrojournal.org/article/S0016-5085(01)18749-4/fulltext in which can be read: "Eight of 22 patients (36%) had only mild symptoms with symptom scores of 2, which would not typically suggest the diagnosis of pouchitis.However, these patients had high endoscopic and/or histologic scores and achieved a total PDAI score of 7 or higher.For these 8 patients, the mean total PDAI score was 9.2 ± 2.2, the mean symptom score was 2.0 ± 0, the mean endoscopy score was 3.9 ± 1.2, and the mean histology score was 3.3 ± 1.3.All 8 patients were treated with a 2-week course of metronidazole or ciprofloxacin and responded with a reduction in the total PDAI of 3 points or more.The mean posttreatment PDAI score was 4.0 ± 1.5, symptom score was 0.6 ± 0.8, endoscopy score was 1.1 ± 0.9, and histology score was 2.3 ± 0.5.The mean reductions of the PDAI, symptom, endoscopy, and histology scores were 5.1 ± 1.8, 1.4 ± 0, 2.6 ± 0.8, and 1.0 ± 0.8, respectively, all of which were significantly lower than the pretreatment scores (P < 0.02 for all comparisons)."

This seems to answer me. I respond to antibiotics, and even when I've got pouchitis I have a very good quality of life which I represent as: "can work, can go out, can eat what I want" and so. And after the course of antibiotics, usually I'm even better. Nevertheless I've got really endoscopic and probably histologic scores... This is like I'm feeling not alone with this and in my ignorance I couldn't find the fact that endoscopy could be really bad but, you can have just a mild pouchitis...

I add also this reference that opened my mind as I really didn't expect it. It's incredible how internet can be resourceful if you can use it well. 

"Ileal Pouch Symptoms Do Not Correlate With Inflammation
of the Pouch" https://www.cghjournal.org/article/S1542-3565(13)01432-8/fulltext

"Pouchitis is difficult to define
because, to some degree, all patients have endoscopic
and histologic evidence of chronic inflammation in the
pouch after pelvic pouch surgery. Furthermore, inflam-
mation may be patchy with areas of scattered ulcers with
normal intervening mucosa, or also may include
nonspecific changes such as loss of vascular pattern or
granularity in the absence of frank, acute inflammatory
changes. Likewise, because most patients have histologic
evidence of chronic inflammation, it is believed that only
acute histologic inflammation is specific to pouchitis.
Functional outcomes also vary and may be caused by
factors other than inflammation, such as patient age,
pouch type, pouch size and compliance, anastomotic
diameter, and sphincter tone.
The PDAI and PAS were developed to allow objective
evaluation of the response of pouchitis to a treatment
under study. However, each of these scoring systems also
include clinical symptoms reported by patients. It has
been observed that patients with objective inflammation
in the pouch can have minimal symptoms and vice versa.
This has led to speculation that the contribution of
symptoms evaluated as part of the pouchitis indices are
nonspecific for pouch inflammation itself and may be
owing to other conditions as described earlier. Shen
et al 1 observed that, when using the PDAI criteria, 43%
of symptomatic patients with IPAA had no endoscopic or
histologic evidence of pouch inflammation"

To add to the story... "Asymptomatic inflammatory bowel disease with special reference to ulcerative colitis in apparently healthy persons." https://www.ncbi.nlm.nih.gov/pubmed/11280543 That's leading me to think that endoscopic examination is just one chapter of the story...

Don’t worry, bio drugs will take care of it. I’m on Entyvio 3 years strong! After almost losing my pouch. Good luck. 

I wonder about this too. I had my takedown about 7 months ago and Have had symptoms on occasion where, and this is just the best way I can describe it, I feel like I have a sock shoved up my butt haha. not severe pain, just sort of... inflamed feeling. I still have about 5 bathroom trips a day. occasionally will bump up to 7 and I have daily nagging stomach aches in the evening. I wake in the morning and feel fine but once it starts I notice i dont pass as much gas and that makes me feel a little worse. I still do what I want, eat what I want, no severe urgency issues but it just sort of "pops up" and will last about a month at a time then a noticably worse pattern will happen and ill go on canasa for a month, get better and it starts again in another month or so. my last scope during symptoms suggested cuffitis according to GI. She says if it happens again we need to discuss long term goals to treat it even if symptoms arent bad.... really dont want to be back on biologics. but i sympathize with you...