I took at look at good-aligned characters with lots of PKs during the last 5-6 years that also don't have detect hidden. Or, at least, not all the time, i.e. I'm going to include conjurers and shapeshifters.

Why good? Because, with a few exceptions, most competent assassins are evil or neutral. Good-aligned characters should be more frequently targeted by assassins than evil. Here's what I found:

Oshui, shifter, 23-1 vs. Assassins (1 assassinate), 47 total PK losses
Vozmuir, warrior, 11-1 vs. Assassins (1 assassinate), 28 total PK losses
Clahier, conjurer, 10-0 vs. Assassins, 12 total PK losses
Azhelak, ranger, 3-0 vs. Assassins, 14 total PK losses
Merrol, shaman, 14-0 vs. Assassins, 19 total PK losses
Caldysias, paladin, 6-0 vs. Assassins, 13 total PK losses
Tolgrumm, paladin, 10-2 vs. Assassins (1 assassinate), 63 total PK losses
Eachainn, invoker, 7-7 vs. Assassins (3 assassinates), 24 total PK losses

Out of those, Eachainn is the only one who really performed poorly against assassins relative to the success he had against other classes. Interestingly, he also did poorly vs. rangers (2-3), invokers (1-1) and necromancers (0-3).

Granted this is a very small sample size and some of these characters are 6 years old. Also I'm looking only at characters that enjoyed PK success; it could be that non-PK-savvy players are especially vulnerable to the assassin class in ways more-PK-savvy players aren't.

For fun, here are stats for some 2012+ PK-savvy battleragers without detect hidden:

Salyeris, bard, 8-1 (1 assassinate), 64 total PK losses
Lohakahn, warrior, 5-2, 89 total PK losses
Hexugar, warrior, 4-0, 28 total PK losses
Akedeh, warrior, 6-0, 67 total PK losses
Bosephus, warrior, 12-0, 21 total PK losses
Aulrathdien, warrior, 6-0, 3 total PK losses
Kontoln, warrior, 6-0, 95 total PK losses
Erighan, warrior, 3-3, 37 total PK losses

Of these, Erighan is the only one who didn't out-perform his overall PK ratio against the assassin class.