I've NEVER come across "fake" LM386 ICs, and I've been buying them since the late 70s. There are different suffixes for the '386 - N and M - which give differing output powers.
Many "designs" omit the bypass capacitor on pin 7, and forget to decouple the supply close to the power pin 6. It's also necessary to connect a "Zobel" network to the output - pin5. This network should be a 10Ω resistor in series with a 47n capacitor from pin 5 to ground. The grounding of the IC is also important - a low impedance path is essential. The "gain set" pins - 1 and 8 - also need to be dealt with.
There are many "second source" suppliers of these ICs, but they're all good copies of the original. It's such a cheap and simple IC that it's pretty much impossible to get wrong!
If you pay close attention to the datasheet and design accordingly, the results are usually excellent. It's not a particularly low noise or low distortion IC, but it's good for its intended purpose - a cheap and simple ½ Watt battery-powered audio amplifier.
The datasheet is available at
http://www.ti.com/lit/ds/symlink/lm386.pdf
If you want to make a simple guitar distortion pedal, the '386 isn't the way to go - it's too hissy.
Get a TL071 or similar low noise op-amp, and build a simple voltage amplifier with it - high impedance input (~500kΩ), low impedance output. Feed the output through a DC blocking capacitor of 10µ, through a 4k7 series resistor, into a pair of 1N4148 diodes to ground. Put a 10k volume control across the diodes, and take the output from the wiper. It's usually a good idea to make the op-amp gain variable too, by using a logarithmic pot in the negative feedback loop. There are loads of circuits online for this kind of thing.