If you join a server like LemonPunch or Fragnet using a public account, the server admins will see "Multiple users from one login." They will permanently ban that account from their servers. Now the account is useless.

Some reward websites generate revenue through surveys and use the profits to maintain a pool of shared accounts for their users. Risks and Pitfalls of Public Steam Accounts

Do you have a friend who already owns GMod to use ? Share public link

Most listings claiming to offer the "best" free accounts come with severe hidden costs.

A social deduction game based on deception. DarkRP: A massive roleplaying mode simulating city life. The Reality of "Free Steam Accounts with GMod"

If you do acquire a secondary account, ensure it is not linked to your primary email or phone number to prevent any cross-contamination if the secondary account has issues. Maximizing Your GMod Experience

Discord servers and Reddit communities (like r/FreeSteamAccounts) sometimes host giveaways. A generous user buys a cheap key or creates a new account with GMod and posts the login details.