Look at this and repeat after me I will ignore the dots when I need to but they are still my friend. I will ignore the dots when I need to but they are still my friend. I will ignore the dots when I need to but they are still my friend.

You dont mention your level of playing.Do you play scales? I am trying to figure out in my head how you would be able to play even a 12 bar blues on rhythm outside of G and A and B on the low E and not land on a fret without a marker or even run a scale.So if your playing E-A-B you have to go 12-5-7 and cant go open -open-2 is that right? Is it a mental block or do you feel lost and not sure of unmarked notes.If it is the latter just start playing an hour a day out of your routine on only unfretted keys and soon it will all fall into place.As F-F#-C and D are all guitar friendly keys. I know a lot of good players who dont like plaing in Ad-Bd-Ed HORN KEYS as there not as sure but you have to work through this.I for one would not buy a guitar I dont care how great it is that does not have fret markers and I see a lot of them today but I am not comfortable on them and I know a lot of people feel the same .I wish you would go into a bit more detail and maybe we can get you through this.