Here's another one: my late husband and I became mildly friendly with a woman who ran the bar in a hotel in Germany that we sometimes stayed in. She was very jolly and chatty. Fast forward a couple of years -my beloved husband suddenly died (very traumatic night - he was ill just one hour, died in my arms before medical help could arrive) - we'd been married only three years.
I returned to live in the UK. German woman had kept in touch and she started dropping heavy hints about coming to visit. Fine, I said, we could meet up for lunch or something - after all, she was a jolly soul, and only a few years younger than I (both in our fifties then). So then she started banging on about how expensive hotels in London were, couldn't she stay with me, it'd be such fun ... mug that I am, I weakened. So on the day she was due to arrive, I was having my coffee and toast at 9 a.m. when she turned up, having arrived at City Airport. I offered her some toast and she said didn't I have any wine?! I mumbled something about some chardonnay in the 'fridge and she said that'd be perfect. And could I make her an omelette, perhaps with some smoked salmon?
I soon found out how she managed to be so jolly - she was permanently sloshed. After her breakfast wine, she'd go off to meet friends in various London drinking clubs for more booze. Then to a pub for pre lunch drinkies, then long long lunch with - you've guessed - wine and brandies to finish off. Another drinking club in the afternoon, then she'd turn up at my place to change for dinner, necking whatever wine I had (and to be fair, she brought back bottles herself and always offered me some)
Boozy dinner, of course - then a club or too. I spent a day out with her so I know just what her routine was - never again!
Her liver, of course, was her own affair but God, she was annoying when it came to the phone. I had just one line and in those days, dial-up internet. So if phone used, internet not available, and vice versa. She unplugged an extension and plugged it into her bedroom, and whenever she was in, she was on the bloody phone ALL the time, I assumed talking to her British friends. Wrong! Turned out she was phoning mates all over the bloody world - nothing important, but relating who she'd met, where she'd been boozing, what she'd had for lunch/dinner and what she'd bought. When she'd finally left, my phone bill was well into three figures - for that one week!
I realised, from her ramblings, that she was a sort of 'professional mistress', to put it charitably. She had a stable of married lovers, who seemed to pay for everything, including her air far to London, her rent, lots of 'presents', any inconvenient bills. Particularly unpleasant was the way she was so disparaging of their poor wives, laughing and sneering at them. She then told me that she kept in touch with even the lovers who weren't even lovers any longer (hmmmm ....blackmail, I couldn't help wondering?) apart from the THREE who had committed suicide 
But what finally did it for me was when we were talking about my late husband, what a lovely guy he was etc., and she told me that she 'could have taken him away from me any time she liked, but she chose not to ...'
For some years after, she phoned often dropping hints about another visit, but I was polite and firm - NO bloody way. I heard earlier this year that she's suffered several strokes. I actually felt quite sorry for her, to be honest. But the amount she drank, I'm amazed it didn't happen earlier.