2SJ162 and 2SK1058 prone to counterfeit ?

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No. This means that semiconductors and other parts bought in China are likely to be fakes.
Especially discontinued audio parts (I know the lat FET discussed here are still in production).

I heard of serious problems a lot of companies experienced during the latest economy panic with the parts they stocked from China. Fakes, fakes, fakes. E.g. bought a reel of semis, first 100 parts okay, 2900 without dies inside and so on. Even worse to receive parts of poor quality that look good and spec like the originals but fail in field later.

Btw: First time I agree with Nagys somehow. ;)
Yes Tekko, they're fake as well. Let's just put it this way, all electronic parts from China are guaranteed to be fake.

A lot of the parts they either manufacture themselves, or purchase the very lowest quality possible and relabel them with name brands, logos, markings, etc.

Sometimes it's even blatantly obvious that plastic capacitors, transistors have been sanded off and stamped with a brand name label.

Stay away!!!!!!

You can get cheap parts from Newark, Mouser, DigiKey, Farnell, etc. Why waste your time?
The higher the price of the original part the more the Chinese fakers profit from faking and thus the more likely they will do it.
Sometimes fakes are more or less obvious but some parts may even pass the quality control of big companies that own good tools and trained persons to find fakes.

Another story is genuine parts that failed QC, were thrown away, stolen from trash, packed and sold.

Buying parts from contracted distributors only is a good way to prevent buying fakes.

What I really, really do not understand is this:
for example this particular ebay seller sells electronic parts exclusively. Many of the offers are the same type semiconductors over and over again. The seller has about 14000 feedbacks from buyers, very, very predominantly positive. The past year one can not even spot a single negative feedback comment where a buyer complains about having received fake semiconductors (> 10000 sales after all).
How can this be if this stuff is supposed to be all fake?
Does really nobody test none of items they get?
I understand that a 100% reliable test ist not easy or not at all possible finally (at any rate not for the average Diyer) but with this amount of sales one would assume that there must be at least a few competent buyers which do have the facilities AND who DO actually TEST them.
What I`m missing?
The reason i buy my stuff on ebay is becauce i buy bulk to last me a while, if i had to use digikey or mouser, i wouldent be able to afford to build even one channel of my mosfet amp.

My prototype contain 2N5401 and 2N5551 from china and its working no prollem, i cant remember where the IRF540/9540 are from since i bought those as a bag of 100 or each several years ago and i still have half of them left, well i have more of the 9540 since i dont use those as often.

The BD139's in the bias cir are from china as well.

The quite expensive IRFP240/9240 were from china and those survived quite a lot of overcurrent up to 13A due to a flaw in assembly, and continued to live for the rest of the day in around 100mA bias before failing in the afternoon.

If those had been fakes, they'd blown instantly, not take abuse and live for a full day afterwards.

I think this fakery scare is taken a bit too seriously. After all, most components today are made in china or japan, not in usa as many on this forum think.

I havent had a prollem this far with fakes.

Im willing to bet that the fakery mostly if not only circle around the more high end and obsolete parts.

Im not worried about the 2500pcs resistor kit and the 5k multiturn trimpots beeing from china since china and japan are the only countries manufacturing components like this nowdays.

Silicon valley only produce computer stuff for nasa, and such, everything used on consumer products are made in china, japan or taiwan.
Those who buy transistors from China are not competent buyers to begin with! Yet alone have any ability to do a proper test. Most of these transistors will work, hence is why people leave a positive feedback at the beginning. They'll fail later on. They'll also sound like complete garbage, but most builders are too proud of their own work to recognize that fact. A lot of small time repair shops also buy from eBay in order to save a few dollars. And it continues on and on.
Nobody buying semiconductors on ebay is able to test them. Someone who has the extremely expensive equipment to test a semiconductor doesn't buy on ebay. They receive parts that work an leave positive feedback. I wouldn't say that they will fail for sure but it is possible they are below spec, low quality parts.

They'll also sound like complete garbage, but most builders are too proud of their own work to recognize that fact.
Good point. I think this is true but not (only) related to parts. ;)

DIYers have way too low quantities for failure statistics. And if a part fails it is hard to trace back.

Damage for DIYers is negligible in most cases their amp won't kill a speaker. If it's broken they can fix it and maybe even enjoy fixing it.
For a company the situation is more serious.

As of 2009, the percentage of global semiconductor production capacity located in the United States was 14 percent, down from 25 percent in 2005 and 17 percent in 2007. Japan has the highest share of global capacity (at 25 percent), followed by Taiwan (18 percent, up from 11 percent in 2001), Korea (17 percent, up from 11 percent in 2001), Europe and the Middle East (11 percent), China (9 percent, up from 2 percent in 2001) and Southeast Asia (6 percent).
So that means every consumer product that say "made in china" likely contain all fake components ?

All JUNK... I would not even consider walmart or other chinese garbage... throw it away in 6 months.. :(
I get my OPS devices for $1.40 apiece - mouser ... all are original , none are subprime. They sound AWESOME!!

Mouser will tell you the origion ... ON is from Malaysia , caps are panasonic FC (taiwan) , only my led's are china (no problems yet).
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it´s not just about failure, but specific electrical properties and sonic performance. A fake has nothing to do with the original die design, it´s just something made with a simple production technique, using a one-step diffusion process and should be considered worthless.
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