I've implemented UBI in a unified monetary system which attempts to solve most of these issues - https://civil.money/about
The way it attempts to prevent people abusing its UBI is:
- Makes all transactions/data publically quantifiable, and uses a number of peers to corroborate all data in a consensus model.
- Has a simple credit rating system as well as attributes to infer a person's particular life circumstance "at a glance" for day-to-day essential purchases, however ultimately it is up to each individual on whether or not to accept a person's money. Transaction history can be closely scrutinised/sources traced for higher cost purchases to determine level of legitimacy (its implicit taxation system does this very thing as well behind the scenes.) This is conceptually not much different to what banks do today for any loan.
- Turns the concept of money on its head and removes the that artificial sense of scarcity (debt) that we're all so scared of today.
- Pegs its value at a constant of time/labour to prevent inflation.
- UBI along with inverse-taxation is actually the money creation source.