The last guest we had at my house was an impromptu stay over by my aunt (about 12 years or so ago) that i'm assuming was on a weekend. She only lives a 3 minute drive away but couldn't be bothered driving home one night after visiting, which she turned up at tea time unannounced. Her first words were "Don't put too much out for me" and she expected to be fed, despite there only being enough for 4. My dad hated the woman, but went along with my mums wished and everyone else got smaller shares so she could have some too. (very annoying selfish woman, invited herself on holiday with us to spain when i was 14 and my mum let her, didn't tell me dad and sis til it was all booked and aunt promptly ruined the whole trip by being selfish, and controlling where we went, when, how long for etc.)She borrowed a nightie of my mums she never wore (that i used to use for dressing up as a kid and never touched again) and i got turfed out of my bed so she could have it. I don't think she used the shower, i hope to god she washed her hands properly with the soap though!
I buy nice shampoo and conditioning mask type conditioners, but i typically bulk buy them when they're on sale in superdrug (lorreal sun sea and sand mask was my fave, £6 a tub or 2 for £5, no idea how that works but it was brilliant stuff) or occasionally on sale in tesco/asda, some of the larger stores of pound shop occasionally have a nice herbal essences mask tub for £1. I do like caffeine shampoo but i refuse to buy the £6 a bottle stuff like my sister (she has female pattern baldness but surprisingly does have some extra growth from using the alpecin stuff) so i get the brands they sell in bodycare or savers. Showergel i will only use dettol antibacterial stuff, which i've only ever found in poundstretcher, they used to sell big pump top ones, now only squeezy 250ml ones, so i bulk buy and squeeze a couple into the pump bottles.
I don't care if my dad uses my stuff but he doesn't, hes a head and shoulders only kind of guy so if i see it on offer i buy some, i don't remember the last time he bought his own, i notice if he's low and replenish stocks. I think he has his own nivea for men showergel from various birthday and christmas gifts he's working through or he uses the dettol bar soap i keep in the side of the bath.
Due to my OCd we don't get visitors never mind over night guests, but hopefully some time over the summer my best friend aka on/off ex (due to mh issues, both love eachother and hoping to get back together) will be visiting, no idea if it will possibly be over night but if we get back together and he starts staying over i'd buy proper Aussie shampoo as i know it's his favourite, hopefully he'd use my dettol showergel though.