You've received some good information as well as some documentation of some extreme cases.
There are products of all categories which are to be avoided.
I stayed away from tubes for some 7 years because of a bad experience - until I came to understand that there exist many reliable designs to choose from.
If you read the literature from back in the late 1980's on the ARC M-300, you'll find comments in TAS on how HP's sample was prone to blowing up. Of course, the words "blowing up" weren't used, and the amplifier was highly touted in the magazine.
I feel your pain Rrog. I too had problems with a previous generation ARC amplifier from that era - a D115-Mk II. It had a penchant for returning to Minnesota for work. In fairness, I've note not heard of issues with more recent generation ARC gear.
The 6C33B tube was mentioned in this thread. People love the sound of this tube, and yet I know of two manufacturers who will not get within the same zip code as this tube - not because they don't like the sonics, but rather because of its sample to sample consistency.
OTL's - don't criticize the breed because of the Futterman. The Atma-Spheres are bullet-proof and their failure modes are benign (warning - dealer disclaimer).
I've had solid state gear experience failure due to a self destructing electrolytic cap. You don't want a smoking cap in your house, but the fact that it was solid state had nothing to do with a random component failure.
Having said that, some failure modes are more catastrophic than others, and I don't mean to trivialize any of this.
Nothing is 100% risk-free.
Cheers,
Thom @ Galibier