You can meet decent men the minute you step outside your front door. There is no designated building with 'Decent Men Here' on the door!
I think you need to look at what you are doing now. If you sit around in pubs with an aura of 'come on men, I'm available' then that's the type you may attract. They may be thoroughly decent or they may just be looking for a quick shag, like many men in many situations.
As others have said, apps like Tinder are renowned for being hook-up sites where the attraction is purely visual and it's a numbers game. You can try it, but it may take a while to find a good 'un.
What do you like doing? You will find it's much better to meet men doing things you and they have in common so you can judge them better as friends as well as potential partners. So, what floats your boat? Sport? Music (choirs supposedly have a good hit rate!) amateur dramatics (ditto), charity work and volunteering, groups like Meet Up and City Socialiser, singles holidays..... I could go on.
I met DH through a friend who knew his friends who she's met on holiday. I met previous long term boyfriends through work, friends of friends, and even now, in middle age, men have tried to pick me up in the supermarket and on trains.
Widen the net and don't seem desperate to 'meet a man' cos it may well put them off unless they are just looking for 'one thing'.