Quite fun for what it is. I agree with many of the comments suggesting possible improvements, which I'm sure the dev is checking out. I like the humor and I'd be glad to see a Tequila Zombies 2.
*Level 13*
1. Apply the vertical belt. 2. Spray paint pink. 3. Remove the vertical belt. 4. Apply the horizontal belt. 5. Spray paint pink again. 6. Remove the horizontal belt if you want and you'll see that you have that white dot. 7. Apply both belts. 8. Spray paint cyan. 9. Remove both belts. Voila!
This game was VERY fun. Definitely repetitive, and I wouldn't want to play it twice, but it was extremely well-done. Some of the bosses were a bit messed up (buggy) - for example, when the final boss was blowing fire, I respawned once and died instantly by him blowing me off the stage.
This draws on elements from many successful 2D run-and-guns (e.g. Contra), making for a quality product. 5/5 for quality, though I'm rounding up a little.
I'd really like to see more from this author as well as some work fixing the bugs and maybe adding some additional modes or features (like new guns - so as not to alter the balance, maybe you could make them available only in as special mode; a rocket launcher comes to mind) to make this game even better.
Again, very impressive!