On 
there’s a large thread of people saying all these horrible things about daily life in the USSR countries. Things about how hard it was to get light bulbs, how there were black markets for everything, political disappearances, etc.
How much of this is true? Has any of these narratives been debunked, and if so what are some good sources to get accurate accounts of what daily life was like before Pizza Hut came to Moscow?
A thing to remember: The Soviet Union fell 32 years ago, anyone under the age of about 40 does not accurately remember living in a Soviet country. Most of the people responding to the thread are relying on second hand knowledge or memories which come from the post-soviet collapse.
Now to your examples:
Black markets: the SU did in fact have black markets for consumer & luxury goods. Broad explanation: the SU preferred to invest into heavy industry at a direct cost to light industry while having a generous minimum wage (for the CoL). Result: large pool of consumers with excess cash and a shortage of supply, conditions ripe for black markets.
Light bulbs: lightbulbs require specialized machinery to mass produce, so like razorblades were somewhat neglected
Political disappearances: short answer: yes, political dissidents were occasionally arrested.
Followup: it’s also important to remember that the SU fell apart, it happened for a reason and stories are going to bias towards the bad side, if you want a more neutral perspective then open up red note and ask people how China is (or watch Luna Oi for a Vietnamese perspective)