How to find out if I am sudoer

I don't think this is possible because sudo will not know that a user doesn't have a password or that it's the empty string until it (sudo) presents the password, empty or otherwise, to the PAM module for validation. Therefore it will always need to request the password from the user, before proceeding.

Your only recourse here is to configure users that do not require the use of a password with the NOPASSWD option in your sudoers file. But this is highly insecure, and I'd recommend you seriously consider what your ultimate goal is here before proceeding with that method.

...so I don't care about security...

First set a "blank" password

This U&L Q&A titled: How do you create a user with no password? suggested using this method which worked for me.

$ sudo passwd --delete samtest
Removing password for user samtest.
passwd: Success

Now test it out

Now add a line like this to your /etc/sudoers file. NOTE: Always edit this file using sudo visudo.

samtest ALL=(ALL)       NOPASSWD: ALL

Now try logging in as user "samtest" without any password.

$ su - samtest
$ 

Now try using this account using sudo:

$ whoami
samtest

$ sudo echo

$ 

As root edit /etc/sudoers and place the following line:

youruser    ALL=(ALL) NOPASSWD:ALL

after

# Allow members of group sudo to execute any command
%sudo   ALL=(ALL:ALL) ALL

In this way you will be capable to execute all commands that require sudo privileges passwordless.

In order to use sudo and be prompted for a password you need to remove

NOPASSWD:ALL