New to Vinted, couple of questions please

[Mojitowithice]

I’ve seen a dress that I really like but there’s no make an offer or buy now button. I messaged the seller 4 days ago but haven’t had a reply.
The Sellers feedback is mostly ‘auto feedback, sale not completed’ I presume this is some sort of scam?

Also, I sold a tee shirt described as good and the recipient said it had holes in it. I’m fairly confident it didn’t when I posted it. I offered a full refund and have chalked it down to experience but how did I stop this happening again?

My other sales have been very positive with nice friendly messages so it’s not all bad.

Any tips or advice gratefully received.

OP there are comprehensive Vinted threads on here already, tips, advice, bewares

I think if there's no offer/buy button, it may mean the shipping options enabled by the seller doesn't match those available in your location. Either that or a glitch!

TBF I'd probably avoid someone with auto feedback of that nature.

Thank you.

Now I’ve had a very low offer on something and declined, is that poor form?
I think I’ve realistically priced it and it’s got 4 favourites

The no offer/buy will be to do with shipping settings. If the carrier they've picked doesn't deliver to your address or the carrier won't take the item (some are fussy about liquids) there won't be a buy option.
For offers you can accept or decline as you feel fit. It's not bad form to offer, it's not bad form to decline.