Don't worry too much about that!
Worse is writer's block brought on by
your own personal criticism of your work.
I've come to realize (from my own experience, and reading about others) that a good method is to do writing (or any other creative endeavour) in phases:
1 - (Brainstorming phase) get an idea, write it out, record it,
save it somehow, and keep it around.
(This part I find easy - tons of song idea snippets laying around). No being critical - just get it down on paper, tape, whatever. Whenever the idea occurs to you, stop what you're doing, and capture it.
2 - (Hard work phase). Set time aside to work on material - and dig in to your idea pile and look for the gems in the pile of ideas. Take a promising sounding one and work on it. Put that verse/chorus pattern together, try to add that missing guitar chord, push it thru to completion. This might include doing a rough cut demo version, or just simply a complete set of lyrics and
acoustic guitar chords written down. Only work on the ones that really do something for you, unless you're stuck, then work on the less appealing ones - you never know what will come of it.
3 - after a while, you hopefully have a folder full of more or less complete first draft songs. Search these for the ones you love most. Take the "best of" songs and polish them up as much as required. If you don't love them, just keep them in the folder as raw material for new songs. Only show/record/perform the songs you really love - if you don't love them, they
won't likely come across for anyone else either, cause your performance won't shine if you don't like it!
Bottom line is to write way more stuff than you need without any thoughts of being too critical, then put on the music critic hat and dig the good stuff out.