The most hated characters for four letter domains might be QXYZ. Names contain them might never be registered.
Let's look at the statistics below.
| 1 qxyz | 2 qxyz | 3 qxyz | 4 qxyz | at least 1 | all combo | |
| total | 170368 | 46464 | 5632 | 256 | 222720 | 456976 |
| percent of all combo | 37.28 | 10.17 | 1.23 | 0.06 | 47.45 | |
| total on 070106 | 78211 | 78211 | 78211 | 78211 | 78211 | 78211 |
| this type on 070106 | 47734 | 14574 | 1068 | 30 | 62308 | 78211 |
| percent of available | 61.03 | 18.63 | 1.37 | 0.04 | 79.67 | 100 |
| percent of the total | 28.02 | 31.37 | 18.96 | 11.72 | 59.38 | 17.11 |
| total on 030106 | 96638 | 96638 | 96638 | 96638 | 96638 | 96638 |
| this type on 030106 | 57286 | 17161 | 1298 | 39 | 74447 | 96638 |
| percent of available | 59.28 | 17.76 | 1.34 | 0.04 | 77.04 | 100 |
| percent of the total | 33.62 | 36.93 | 23.05 | 15.23 | 70.56 | 21.15 |
We divide names into four types. Those contain one of the letters, like GYIL; those contain two of the letters, like DYYO; those contain three of the letters, like RYXX; and those contain four of the letters, like QQQQ.
The row "percent of available" is the percent of the type out of the total available domains. The row "percent of the total" is the percent of the type out of the all domains of this type.
Quite surprisingly, at day one, randomly pick any four letter combination, half of the time it will contain one of the letters! Now a random pick will hit them four out five times. So definitely people don't like them and they are left behind. Like the water is evaporated and only salt is left on the bay land.
So will they be registered finally?
From transaction on the ebay and different forums, we observe people tolerate more and more the so called bad letters. If combinations contain a single bad letter are all registered, we are left with about 15K combinations contain two or more bad letters. Most likely there will be mass buyout if the available domains drop to that level.
There is something interesting here. The domain names contain only the so called bad letters actually got registered at a much faster rate than average. On July 1st, only 12% are left compared with 17% for all. The domain names contain three bad letters is registered at similar rate as overall, 19% left on July 1st.