My parents are landlords. My dad has unfortunately passed away so my mum handles it alone now. The last tenant was in the house for 8yrs. 3yrs ago being in and out of hospital and ill health meant that my mum stopped inspecting. There had been no issues at any inspections so it just didn't enter her head. She did however plan to inspect last year. I know this is heavily naive and if I knew this to be the case at the time I'd have advised her differently and offered to step in for inspections myself.
6 months ago the tenant very suddenly gave notice and moved out, mum went to inspect (I drove her) when the tenant had already left (the tenant wrote a letter and posted the key with it, so there was no time to inspect) What we found was absolute filth. Human and animal shit. Piss up the walls. Rotting food, the original furniture provided with the house was smashed to bits. Parts of the doors smashed in. The patterned red carpet was so dirty it looked a dark brown and you could see no pattern. There was a wet pile of bin bags up against the kitchen door, covered in fruit flies and maggots and god knows what else. I suspect this was the cause of the mold behind the door (the only mold on any fixtures we found - plenty of moody food, clothes and bits of carpet tho) Ashtrays turned up everywhere. The sofa had fag burns all over. Toilet ripped off the wall, bathroom sink smashed on the floor. Light fixtures hanging out by wires. There's more but honestly it would take all day to write it all. I can't think of anything that's been left undamaged.
Since then, the holes in the walls have been filled in and doors replaced. Carpets ripped up. A team of cleaners got the worst of the cleaning done. The total bill for this so far is £8000 (the cleaning alone was 2800, Trust me when I say I don't blame them for that price. It was horrific and I couldn't stand in the house for more than 10 seconds without heaving). Furniture cleared out etc etc.
My mum has sent the bill for all work to the now ex tenant, there was an initial response where they offered a £15 a month payment plan. My mum cried to me about it but accepted (fearing that if she pushed they'd pay nothing) after 2 months they stopped paying. She cannot at this time afford to have further works done. The total to have everything replaced even using the cheapest materials and not replacing like for like is about £35,000. She's looking at selling but has been advised that she'll be looking at maybe £45,000 as a sale price in the state it's in (in decent condition the house would be worth approx £150k).
My mum has been in contact with a solicitor but via some digging we've found out that the tenant has left the country - for Australia. Solicitor advises that if this is the case mum has an extremely slim chance of actually recovering any monies owed and chasing it across the globe would cost thousands upon thousands and likely require an international debt collection agency of some kind and the tenant can easily just ignore it.
Aibu to think this is fucking shit? 
I know that my mum should've done things differently but it seems very unfair that you can just book a flight and go to skip out on your financial responsibilities