In general, everything is clear with the categories of rooms (luxury / standard / economy); but even in one segment the rooms are different in terms of comfort and presentability. You can get a room with a sea view (for a small additional fee), or you can live with a view of the trash heap.
The distribution of numbers is no coincidence. Tourist groups or those who made reservations through an aggregator site settle in worse rooms. Using the website of the hotel itself, you can apply for a good room, and if you are also members of the loyalty program - even more so!

Loyalty program
It is most beneficial to use this feature in a large hotel chain, there are not so many of them: Hilton Honors, Melia Rewards, Club Garson and a few more.
Choose one and reach a high level of loyalty in it in order to receive pleasant bonuses (free breakfast, best rooms, etc.).
Booking sites
Do not forget to compare prices on different aggregators and on the hotel website: you may find a difference in the prices offered by the terms and conditions. The reservation made on the hotel website is more reliable: the intermediary resource may fail and the computer will not display your reservation.